[UNIT Laboratory]

BRIGADIER: Now just a moment.
SARAH: Look, Brigadier, look. I think it's started.
BRIGADIER: Oh, well, here we go again.
(The brown haired man starts to wake and mumble in the background. The Brigadier picks up the telephone.) 
BRIGADIER: Get me the medical officer. Lieutenant Sullivan? Emergency. Come to the lab at once, please.
DOCTOR: Human history.
BRIGADIER: What's he talking about?
SARAH: It's something that happened when we first met.
DOCTOR: I tell you, Brigadier, there's nothing to worry about. The brontosaurus is large and placid.
(A naval officer enters. Everyone say Hi! to Ian Marter.)
HARRY: This the patient, sir?
DOCTOR: And stupid. If the square on the hypotenuse equals the sum of the square on the other two sides, why is a mouse when it spins? Never did know the answer to that one.
(Benton enters. He has lost his sergeant's stripes and gained a crown.)
BENTON: Excuse me, sir. The daily reports.
HARRY: Take him to the sick bay. I'll make a proper examination there.
BENTON: What's happening, sir? Who's
BRIGADIER: That, Mister Benton, is the Doctor.
BENTON: You mean he's done it again? He's changed?
BRIGADIER: Apparently. Saw it happen this time. Lieutenant Sullivan?
HARRY: Yes, sir?
BRIGADIER: I'm placing the Doctor in your personal charge. He's to have your full attention.
HARRY: Right-o, sir.
(Harry and his assistants leave with the Doctor and Sarah.)
BRIGADIER: Right, anything urgent, Mister Benton.
BENTON: No, sir. Just routine.
BRIGADIER: Yes, everything seems pretty quiet.

[Weapons Research Centre]

(We see through the multifaceted eyes of something as it approaches a sentry on duty. He fires his pistol at it before being attacked. Then the thing uses it's metal claws to rip through the barrier and its padlocks. On it goes, into the centre, beeping quietly to itself. Guard dogs bark, then whimper and run before it smashes its way into the building. Once inside, it goes down a corridor, rips open a strongroom vault door and removes a paper labelled Top Secret.)
BRIGADIER [OC]: A complete set of plans for the new disintegrator gun.

[UNIT Laboratory]

SARAH: Stolen? Who by?
BRIGADIER: No one saw them. Probably enemy agents. Small commando squad. They found heavy vehicle tracks. You realise of course, Miss Smith, all this is top secret?
SARAH: Then why are you telling me?
BRIGADIER: Well, because I. Because there's no one else I can tell.
SARAH: The Doctor's still unconscious? Oh, he'll be all right. I know he will.
BRIGADIER: He used to drive me mad, but I miss having him about. You know, he'd have been interested in this robbery. There's some very strange features.
SARAH: Actually I want to ask a favour of you.
BRIGADIER: Yes, of course.
SARAH: Er, you know Think Tank, the frontiers of science research place? All the latest of everything under one roof?
BRIGADIER: Yes, what about it?
SARAH: Well, now and again, exceptionally favoured journalists are allowed to visit it, and, well, for ages now I have been dying to
BRIGADIER: You want me to get you a visitor's pass.
SARAH: Oh, please.
BRIGADIER: Nothing simpler. Come to my office and I'll fix it straight away.
SARAH: And could I see the Doctor before I go?
BRIGADIER: Yes, of course.
SARAH: You're sure you've got the right man to look after him?
BRIGADIER: Young Sullivan? Oh, he's a very fine chap. First class doctor.
SARAH: Seems a bit old fashioned.

[UNIT corridor]

BRIGADIER: Nothing wrong with that, Miss Smith. You may not have noticed, but I'm a bit old fashioned myself.
(Around the corner, a figure in nightshirt is trying to put on a jacket whilst carrying a pair of boots. He hides as the couple pass by.)
SARAH: Oh, nonsense, Brigadier. You're a swinger.
(The Doctor comes out of hiding and goes into the laboratory.)

[UNIT Laboratory]

(He spots the Tardis.)
DOCTOR: Ah!
(But it is locked.)
DOCTOR: Key. Key, key, key, key. Key, key.
(He searches the jacket pockets. Nothing. Then he shakes the boots and there it is.)
DOCTOR: Yes, of course. Obvious place.
HARRY: There you are. Now come along, Doctor, you're supposed to be in the sick bay.
DOCTOR: Am I? Don't you mean the infirmary?
HARRY: No, I do not mean the infirmary. I mean the sick bay. You're not fit yet.
DOCTOR: Not fit? I'm the Doctor.
HARRY: No, Doctor, I'm the doctor and I say that you're not fit.
DOCTOR: You may be a doctor, but I'm the Doctor. The definite article, you might say.
HARRY: Look here, Doctor. You're not fit
DOCTOR: Not fit? Not fit? Of course I'm fit. All systems go!
(The Doctor karate chops a handy brick in half then does some vigorous running on the spot.)
HARRY: I say. Well, look
(The Doctor takes Harry's stethoscope and holds it to his chest. Harry listens. Then the other side.)
DOCTOR: Hearts beat?
HARRY: I say, I don't think that can be right.
DOCTOR: Both a bit fast, are they?
HARRY: Well, I
DOCTOR: Still, must be patient. A new body's like a new house. It takes a little bit of time to settle in.
(The Doctor sees himself in a mirror.)
DOCTOR: Oh. As for the physiognomy. Well, nothing's perfect. Have to take the rough with the smooth. Mind you, I think the nose is a definite improvement. As for the ears, well, I'm not too sure. Tell me quite frankly, what do you say to the ears?
HARRY: Well, I really don't know.
DOCTOR: Well, of course you don't. Why should you? You're a busy man. You don't want to stand here burbling about my ears. Neither here nor there. I can't waste any more time. Things to do, places to go. I'm a busy man too, you know. Thank you for a most interesting conversation. Must be on my way.
HARRY: There is absolutely no question of you leaving, Doctor. Now, you go back to the infirmary, I mean the sick bay, get into bed and stay there until I say that you can get up.
DOCTOR: How can I prove my point?
(The Doctor finds a long piece of rope and holds an end in each hand. He stands close to Harry.)
HARRY: I think I ought to warn you, Doctor, that there's grave danger of myocardial infarction, not to speak of pulmonary embolism. Yes, I should, I should
(The Doctor starts skipping with the rope, forcing Harry to join in.)
DOCTOR: Mother, mother, I feel sick. Send for the doctor quick, quick, quick. Mother, dear, shall I die? Yes, my darling, by and by. One two three four.

[UNIT corridor]

BRIGADIER: There's only one place he can be.
SARAH: I thought you said Doctor Sullivan was looking after him.
BRIGADIER: He's supposed to be.
(They go into the laboratory.)

[UNIT Laboratory]

(There is a banging noise.)
SARAH: Cupboard.
(She opens it to reveal Harry lying with his feet fastened up in the air.)
SARAH: What are you doing down there? Where's the Doctor?
HARRY: Tied me up and hung me up in here like a pair of old boots.
BRIGADIER: Well, where is he?
(The Tardis starts up.)
BRIGADIER: Ah, too late.
SARAH: No! No, Doctor, wait! Doctor, listen. Please, it's Sarah!
(The Tardis stops and the door opens.)
SARAH: Doctor!
DOCTOR: Hello. Come to see me off, have you? Well, I hate goodbyes. I'll just slip away quietly.
SARAH: No, no, Doctor. You can't go.
DOCTOR: Can't? Can't? There's no such word as can't.
(He slams the Tardis door in her face. After a moment, it opens again.)
DOCTOR: Why not?
SARAH: Well, because you're not. Well, because the Brigadier needs you. Don't you, Brigadier?
BRIGADIER: What? Oh, yes, of course. Depending on you.
DOCTOR: What for?
SARAH: Er, well, there's been this robbery, hasn't there, Brigadier. Some kind of secret weapon.
BRIGADIER: Ah, yes. Very serious business.
SARAH: And I mean, you are still UNIT's scientific advisor. Remember? Well, you can't go rushing off and leave them in the lurch.
DOCTOR: Can't I? Goodbye.
(The Tardis door shuts again.)
HARRY: Er, excuse me, sir.
BRIGADIER: What?
HARRY: Could you oblige?
BRIGADIER: Oh, yes.
(The Brigadier unties Harry's feet as the Doctor looks out of the Tardis again.)
HARRY: Thank you.
DOCTOR: Excuse me.
BRIGADIER: What?
DOCTOR: Haven't me met somewhere before? No, don't tell me. Alexander the Great? No. Hannibal? No. Ah. Brigadier. Brigadier Alistair Gordon Lethbridge Stewart. How are you?
BRIGADIER: Very well, thank you.
DOCTOR: And Sarah Jane. Well now, isn't this nice? What was that you said about a secret weapon?

[Stores room]

(The metal monster rips its way through an electrified fence. The security man in the stores quickly bars the door and goes for the telephone, but before he can utter a word the whatever it is has battered its way in, throttled him and ripped the telephone from the wall. Then it goes to the racks of parts on the wall and carefully selects the items it needs according to the beeps it is receiving.)

[UNIT Laboratory]

(Harry is using his own stethoscope to listen to both sides of his chest when the Brigadier enters.)
BRIGADIER: Doctor, there' been another. Where is he?
HARRY: In there.
BRIGADIER: He promised he'd
DOCTOR: Ah, Brigadier.
BRIGADIER: Ah, Doctor, we must get moving.
(The Doctor comes out of the Tardis dressed as a Viking warrior.)
DOCTOR: Is something wrong?
BRIGADIER: You've changed.
DOCTOR: Oh, no, not again.
BRIGADIER: No, I didn't mean your face, I meant your clothes.
DOCTOR: Don't you like them?
BRIGADIER: UNIT is supposed to be a security organisation.
DOCTOR: Do you think I might attract attention?
BRIGADIER: It's just possible.
DOCTOR: One moment.
(The Doctor goes back into the Tardis, then re-emerges as the King of Hearts from a pack of playing cards.)
DOCTOR: No? No.
(Next costume - a pierrot. Then -)
DOCTOR: Well, how about this?
(Shirt, trousers, jacket, very long striped scarf and floppy hat.)
BRIGADIER: Much better, Doctor. Now, if you've quite finished with your wardrobe?
DOCTOR: I'll try again if you like.
BRIGADIER: No, let's settle for that, please. Now, Doctor
DOCTOR: Time we were off.
BRIGADIER: Off?
DOCTOR: To visit the scene of the crime.
BRIGADIER: The thing is, there's been another robbery.
DOCTOR: Tell me on the way, Brigadier. Tell me on the way. You must cultivate a sense of urgency.

[Electric fence]

(Harry is looking at the ripped metal while the Doctor examines marks in the ground nearby.)
BRIGADIER: Millions of volts running through the wretched thing, and for all the good it was, it might just. Doctor? Doctor, will you please pay attention.
DOCTOR: Oh, but I am, I assure you. Look.
(The Doctor has a yellow dandelion head in his hand.)
BRIGADIER: Doctor, I have every respect for your concern for ecology, but really, one squashed dandelion.
DOCTOR: Not just squashed, flattened. Almost pulverised.
(The Doctor blows the dust into the Brigadier's face.)
DOCTOR: Now, how did it get like that?
HARRY: Well, I suppose it was stepped on.
DOCTOR: Exactly. And according to my estimation of the resistance to pressure of vegetable fibre, it was stepped on by something that weighed a quarter of a ton.

[Stores room]

BRIGADIER: Funny thing is, they left a lot of valuable and top secret stuff behind. Here's a list of all they actually took.
DOCTOR: Hmm. Just what you'd need for the control circuitry of one powerful, compact technological device. A disintegrator gun, for instance?
BRIGADIER: What do you know about that?

[Outside Think Tank]

(Welcome to Wood Norton Hall, Eyesham. The guard at the gate stops a car.)
GUARD: Yes, Miss?
(Up at the house, a balding man speaks to a woman who has just come outside.
JELLICOE: That journalist girl is arriving. The one with the UNIT pass. Something of a nuisance at the present moment in time.
HILDA: We shall treat Miss Smith exactly as any other visitor.
JELLICOE: I suppose so. I suppose so.
(Sarah walks up and shakes hands with the man.)
SARAH: Hello. You know, it's awfully good of you to allow this visit, Director.
HILDA: I hadn't expected male chauvinist attitudes from you, Miss Smith.
SARAH: I'm sorry?
HILDA: I'm the Director. Hilda Winters. This is Arnold Jellicoe, my assistant.
SARAH: Oh.

[Electric fence]

(The Doctor gets into the back of the Land Rover.)
BRIGADIER: So, what are we looking for?
DOCTOR: Something that brushes chains and electric fences like cobwebs. Something intelligent, that takes only what it needs and leaves the rest. Something that kills a man as casually as it crushes a dandelion.
BRIGADIER: And what sort of something? Is it human?
DOCTOR: I doubt it, Brigadier. More than human, perhaps.
BRIGADIER: Well, whatever it is, how do we find it?
DOCTOR: By locking the next stable door in good time.
BRIGADIER: Huh?
DOCTOR: It, whatever it may be, has stolen the plans for the new disintegrator gun. It has also in its possession the necessary control circuitry.
HARRY: You think it wants to build the gun?
DOCTOR: Why else steal the plans and the circuitry? Now, assuming I'm right, and I invariably am, what is the third vital ingredient?
BRIGADIER: The focusing generator.
DOCTOR: Exactly, Brigadier. Exactly.
(The Brigadier gets on the radio.)
BRIGADIER: Greyhound Leader to Trap One. Over.
BENTON [OC]: Trap One. We read you, Greyhound Leader. Over.
BRIGADIER: Mister Benton, red priority. Emmett's Electronics, a smallish factory in Essex. I want blanket security. Every available man. Air cover as well. I'll meet you there in one hour. By then I want that place better guarded than Fort Knox. Out.
(The Doctor drives the Land Rover away, with Harry in the back.)

[Outside Think Tank]

(Sarah, Jellicoe and Hilda Winters walk along a garden wall.)
JELLICOE: As you've seen, we do most of what's called frontiers of science research here.
HILDA: As soon as our work reaches a practical stage, it's handed over to someone. Someone with more resources and a bigger budget.
JELLICOE: Usually the government.
SARAH: Well, like the new disintegrator gun? You pioneered the research on that, didn't you?
HILDA: Well, yes. I'm not sure you should know about that.
SARAH: Oops. Sorry. Talking out of turn. What's in here?
(Sarah barges through a door clearly labelled Positively No Admittance.)

[Robotics section]

(Along a corridor and into a large room with a just a table in the middle.)
JELLICOE: There's nothing here. Nothing at all.
HILDA: As you can see, it's empty.
(Sarah reads the sign on the door.)
SARAH: J P Kettlewell, Robotics Section. He left some time ago, didn't he? That's right, there was all that fuss about it in the press.
HILDA: Yes, indeed there was. As you probably heard, he turned against conventional science altogether.
JELLICOE: He spends his time on alternative technology, whatever that may mean.
SARAH: What's through there?
JELLICOE: His store room. Professor Kettlewell left some valuable equipment. We're keeping it until he deigns to come collect it.
SARAH: Oh, I see. Oo, funny musty sort of
(Sarah's foot slips and she almost falls. Jellicoe grabs her.)
SARAH: Oh!
HILDA: Are you all right?
SARAH: Just about. Thank you.
HILDA: Well, let's be on our way, Miss Smith. There's still quite a lot to see, you know.
SARAH: Oh, yes, of course. Thank you.

[Emmett's Electronics]

(Sandbags protect a machine gun emplacement on the flat roof above the main entrance, and soldiers take up defensive positions all round the place.)
BRIGADIER [OC]: I tell you, Doctor, I've got the whole place covered.
BENTON: Come along, come along. Get that wire across. Move!
BRIGADIER [OC]: Armed patrols have every inch of the perimeter under observation. Helicopter patrols overhead. Inside that factory is a vault. Not a safe, Doctor, a vault. There's a sentry outside it. Inside the vault there's a casket. A metal casket containing every focusing generator in the place. Believe me, Doctor, the place is impregnable.
DOCTOR: Never cared much for the word impregnable. Sounds a bit too much like unsinkable.
HARRY: What's wrong with unsinkable?
DOCTOR: Nothing, as the iceberg said to the Titanic.
HARRY: What?
DOCTOR: Glug, glug, glug.
BENTON: All patrols posted, sir.
BRIGADIER: Everything secure?
BENTON: Yes, sir. The lads are so close together they're standing on each other's feet.
BRIGADIER: Good. See, Doctor? Not even a rat could get through that cordon. Protected from every side and from above.
DOCTOR: That still leaves one direction.
(The Doctor points downwards. Right on cue, a drill bit comes up through the vault floor. The sentry on duty on top of the entrance to the bunker goes down and opens the door to see where the noise is coming from. He opens fire with his machine gun. The Brigadier, Benton, the Doctor and Harry run towards the noise.)

[Vault]

(The men run into the vault to find a big hole in the floor, one dead soldier, and the casket ripped open.)
DOCTOR: There seems to be a very large rat about, Brigadier.
BRIGADIER: Rat?
DOCTOR: Perhaps you should employ the services of a very large cat.

[Kettlewell's house]

(A very open plan place, with an office area separated from what has become a laboratory just by a few steps downwards. An old, bearded man with round glasses and mad scientist hair is speaking.)
KETTLEWELL: I'm afraid I can't help you, Miss Smith. I don't know why you came to me.
SARAH: Well, I'm not too sure myself, to be honest. I just felt something in the air at Think Tank.
KETTLEWELL: Yes, I severed all connection with that establishment some time ago, when I became completely disillusioned at the direction all our research was taking. The road to ruination. I'm now devoting my life to alternative energy technologies.
SARAH: Solar cells, heat from windmills, that sort of thing?
KETTLEWELL: Yes, as you say, that sort of thing. It's a rich and complex field, and I have a great deal of work to do.
SARAH: Oh, I beg your pardon. Well, I just wondered if they might be carrying on your work in robotics?
KETTLEWELL: No one is carrying on my work in robotics, Miss Smith, because no one has the ability to do so. Good day.
SARAH: Goodbye.
(Sarah spots some rope lying on the floor.)
KETTLEWELL: Good day, Miss Smith.
SARAH: Just going. Thank you.
(Sarah leaves. Kettlewell unearths a sandwich from a pile of papers and takes a bite while looking through the window. Sarah gets into her car and takes the Think Tank pass from her handbag. She makes a decision and drives off.)

[Woodland]

(There is a large steaming hole in the ground.)
BENTON: We think this is the other end of it, sir, only
BRIGADIER: Only? Only what?
BENTON: Only its not a proper tunnel. I mean, no props or anything. Just the earth been shoved aside. Whoever went through it wouldn't be able to breathe.
DOCTOR: Whoever went through it didn't need to breathe.
BENTON: And then there were these, sir.
(Oblong dents in the ground, twice as big as the Doctor's foot.)

[Outside Think Tank]

SARAH: I've er, left my note book in one of the empty labs. I know exactly where it is. I can see myself putting it down. So, if you could just let me pop in and get it, I needn't let your director know what an idiot I've been. Oh, please. Look, my pass is still valid for another ten minutes yet.
GUARD: Wait here, Miss. I'll check for you.
SARAH: Great.
(The guard goes into his hut to make a telephone call. Sarah climbs over a balustrade then runs across the grass to the Robotics Section. If you're interested, this location was also used in Spearhead from Space.)

[Robotics section]

(She touches the patch of floor where she slipped, and sniffs her fingers.)
SARAH: It was oil. I knew it.
(There is a whirring noise, and Sarah looks round to see a giant robot in the room.)
ROBOT: Who are you? Why are you here?
(Sarah backs away as the robot approaches, scanning her with its multifaceted eyes.)

Part Two

[Outside the Robotics section]

(Sarah manages to get out of the room.)
HILDA: Hello, Miss Smith.
SARAH: Look out, there's a great robot in there!
HILDA: Yes, I know. Don't worry, my assistant's dealing with it.

[Robotics section]

SARAH: What?
HILDA: I'm sorry if our little joke upset you.
SARAH: Joke?
HILDA: You were determined to see the robot and so we arranged it for you. That is what you wanted, isn't it?
SARAH: Oh, how very kind of you.
JELLICOE: When we heard that you were in the building, we guessed what you were up to, so I popped in here ahead of you and I activated it.
SARAH: Is it still in there?
HILDA: Oh, yes. Would you like to see it again?
SARAH: Thank you. I'd like that very much.

[UNIT Laboratory]

(The Doctor is lying on the bench with his hat over his face.)
BRIGADIER: Well, Doctor, what are we dealing with? Invasion from outer space again?
DOCTOR: Why should some alien life form invade Earth just to steal a new weapon? If they were that advanced, they'd have weapons of their own. Ha. Rather a splendid paradox, eh, Brigadier?
(The Doctor gets to his feet.)
DOCTOR: The only ones who could do it wouldn't need to.
BRIGADIER: Enemy agents?
DOCTOR: Well, they might steal the plans, but why steal the circuits and the generators? An enemy government would have those resources itself.
BRIGADIER: So where does that leave us?
DOCTOR: I think your enemies are home grown, Brigadier. People with access to technological information and a most unusual weapon. A weapon that walks and thinks. In a word, anthropomorphic.
BRIGADIER: Well, I suppose that narrows the field a bit. Do we know anything else about these people?
DOCTOR: Only that they're prepared to kill to protect themselves. Where's Sarah?

[Robotics section]

SARAH: What's the hold up?
HILDA: Mister Jellicoe is checking over the circuits.
SARAH: Well why is he taking so long?
HILDA: He must be sure that everything is safe.
SARAH: Safe?
(The whirring sound starts up as steel doors part and the robot comes out of its chamber, followed by Jellicoe.)
HILDA: Stop.
(The robot obeys.)
SARAH: It's very impressive, but what's it for?
HILDA: Ask it. It's voice controlled.
SARAH: What do you do?
ROBOT: Insufficient data. Please be more specific.
JELLICOE: It has a terribly literal mind.
SARAH: What is your purpose, your function?
ROBOT: I am experimental prototype robot K one. My eventual purpose is to replace the human being in a variety of difficult and dangerous tasks. Tasks for which I am programmed are mining operations of all kinds, operations involving radioactive materials
HILDA: Terminate.
JELLICOE: It would go on for hours.
SARAH: Why all the mystery? Why didn't you just show him to me when I first came?
HILDA: My dear Miss Smith, why should we? You were a privileged visitor here. You abused that privilege to pry into matters on the secret list.
SARAH: You're right, of course. I'm sorry.
JELLICOE: Not a bit of it. You were simply following the instincts of a good journalist. And now, if you've seen enough?
SARAH: Er, it isn't dangerous, is it?
HILDA: Of course not. Why should it be?
SARAH: Well, it just struck me that it could be a very powerful weapon if it got into the wrong hands. It could be misused.
HILDA: Like this, you mean? This girl is an intruder and a spy. She must not leave here alive. Destroy her.
(Jellicoe shuts the doors. The robot advances on Sarah then stops.)
HILDA: Destroy her.
ROBOT: I cannot obey. This order conflicts with my prime directive.
HILDA: You must obey. You are programmed to obey.
ROBOT: I must obey. I cannot obey. I, I
HILDA: Terminate.
SARAH: Another of your little jokes?
HILDA: A practical demonstration. You must admit it was a convincing one.
JELLICOE: Prime directive, you see. It's built into the robot's very being that it must serve humanity and never harm it.
SARAH: That was a cruel thing to do.
HILDA: Cruel? It isn't human, you know. It has no feelings.
SARAH: Oh, it's got a brain, hasn't it? It walks and talks like us. How can you be sure it doesn't have feelings too? Are you all right?
ROBOT: My functioning is unimpaired.
SARAH: But you were distressed. I saw that.
ROBOT: Conflict with my prime directive causes imbalance in my neural circuits.
SARAH: I'm sorry. It wasn't my idea.
ROBOT: The imbalance has been corrected. It is not logical that you should feel sorrow.
HILDA: Really, Miss Smith, this is absurd. I think you must be the sort of girl that gives motor cars pet names.
(Sarah strokes the robot's metal torso.)
HILDA: Deactivate. You see? It's just a lump of metal.
SARAH: Thank you for an interesting demonstration. I think I ought to leave now.
HILDA: One moment, Miss Smith. If I were to make a formal complaint about your behaviour here, you might find yourself in a very difficult position.
JELLICOE: Dangerous thing, curiosity. Can get you into a lot of trouble.
HILDA: So I'll make a bargain with you. Keep quiet about what you've discovered here, and I'll keep quiet about how you discovered it.
SARAH: Goodbye, Miss Winters, Mister Jellicoe. Oh, please, don't bother to see me out.
(Sarah leaves. Jellicoe checks that she is out of earshot.)
JELLICOE: That was an appallingly dangerous thing to do. Telling it to destroy her. The inhibitor's only just been reset. You know there have been problems. Suppose it had obeyed you?
HILDA: It made an interesting test.

[UNIT Laboratory]

(The Doctor is building a small tower out of anything and everything.)
BRIGADIER: Where do I start looking for this precious conspiracy?
DOCTOR: Oh, it's surely not that difficult, Brigadier? Oh, thank you. There can't be many groups of people with the money and resources to design and build something like
(Sarah enters with Harry Sullivan.)
SARAH: An enormous robot over seven feet tall!
DOCTOR: Yes, something like that. However did you guess?
SARAH: Guess? I've just seen it. I've been talking to it. Brigadier, there's something very odd going on at Think Tank.

[Robotics section]

(The robot's head has been removed by Jellicoe, standing on a step ladder.)
JELLICOE: Screwdriver.
(He makes an adjustment and its left arm rises sideways.)
HILDA: Careful.
(She passes him a can of lubricant.)
JELLICOE: Swab.
(He puts the head back on. The red eyes light up.)
JELLICOE: There. I think that's it.
HILDA: Think? You'd better be sure.
JELLICOE: It's a delicate job. I'm not really trained in this sort of work.
HILDA: Well, we'd better test it.
JELLICOE: This time, emphasise the recall instructions. You know, it refused to return after that last business. I found it wandering near Kettlewell's place.
HILDA: How touching. Perhaps Miss Smith was right.
JELLICOE: What about?
HILDA: Perhaps it does have feelings. It misses Daddy. Activate. Prepare for visual scanning.
(Hilda brings out a projector on a trolley.)
ROBOT: I am ready.
(Hilda switches on the projector.)
HILDA: This man is an enemy of the human race. He must be destroyed.
(A press cutting of a silver haired man with neat moustache is on the wall.)

[UNIT Laboratory]

(The Doctor's tower of odds and ends has grown a lot.)
SARAH: Look, its obvious that that Think Tank lot are involved. Why don't you just raid the place and arrest the lot of them?
BRIGADIER: I very much doubt if I'd get the authority. And if I did, it'd cause so much fuss they'd have plenty of time to hide the evidence. I must have more to go on.
SARAH: More than just my word, you mean?
HARRY: You know, you need an inside man.
BRIGADIER: What?
HARRY: Well, you know, somebody planted on them to keep his eyes and ears open.
SARAH: Hey, you know, that's not a bad idea.
BRIGADIER: It'd have to be someone they'd accept, someone with the proper scientific qualifications.
DOCTOR: Scientific or medical.
HARRY: Oh, I say. Me?
SARAH: Why not? Your chance to be a real James Bond.
HARRY: But
BRIGADIER: Might work. We could fix you up with a cover story.
HARRY: I could wear a disguise.
DOCTOR: I'd like to talk to Professor Kettlewell.
(The tower topples over.)

[Kettlewell's house]

KETTLEWELL: I tell you as I told this young woman, I know nothing about the Think Tank and its activities. I severed all connections with them
SARAH: But I saw the robot.
KETTLEWELL: What's that? Oh no, that's impossible. I gave orders for him to be dismantled.
BRIGADIER: Professor Kettlewell, this is an official inquiry and I must ask you
KETTLEWELL: Would you kindly put those papers down, sir?
DOCTOR: Plans for a new solar battery.
KETTLEWELL: That folder is private and confidential.
DOCTOR: This will never do, you know.
KETTLEWELL: There are many years of
DOCTOR: If theta over x coincides with your disputed factor, you're losing half your output.
KETTLEWELL: Oh, rubbish. I checked all those calculations myself.
DOCTOR: Look, the error's in the third part of the calculation.
(Kettlewell gets out a pocket calculator and starts tapping at it.)
KETTLEWELL: Bless my soul.
DOCTOR: But you're doing vital work, Professor. Earth's human race should have started tapping solar power long ago.
KETTLEWELL: This new solar battery will provide an endless supply of pollution free energy at a fraction of the present cost and they haven't the wit to see it.
DOCTOR: Well, there you are.
KETTLEWELL: Yes, you know, I've explained it to them over and over and over again till I'm blue in the face.
DOCTOR: People never can see what's under their noses and above their heads.
BRIGADIER: Concerning this robot
KETTLEWELL: You be quiet, young man. You know, ever since the days of Galileo
DOCTOR: And Copernicus.
KETTLEWELL: And Copernicus, scientists have had to
DOCTOR: Professor, I think you ought to tell us about the robot.
KETTLEWELL: Yes. It was the last project I worked upon before I decided to leave. I gave orders for him to be dismantled. It was like putting my own son to death. I thought it was for the best. His power, his capacity to learn had begun to frighten me.
SARAH: But it wasn't destroyed, was it.
KETTLEWELL: I don't know. That woman, Winters, might have countermanded my orders.
BRIGADIER: Could the robot have been made to carry out these break-ins?
KETTLEWELL: No, no, no. You say that people were hurt, even killed?
BRIGADIER: Yeah.
KETTLEWELL: Oh, it's out of the question. You said he refused to harm you, didn't you? Yes, well, I gave him my own brain pattern. He has my principles, my ideals.
DOCTOR: But the circuitry you built could be altered or tampered with.
KETTLEWELL: Doctor, not even I could effect such a change. As for Jellicoe and Miss Winters, well, they're incompetent nincompoops.
SARAH: Maybe, but I wouldn't put it past them to try.
KETTLEWELL: If they force him to go against his prime directive, they'll destroy his mind. He'll go mad.

[Office]

(An alarm rings, and the man from the press cutting enters wearing a dressing gown and turns on the lights. He goes to a cupboard on the wall and unlocks it to check that the safe is still locked. Then he picks up the telephone. Just then the wood panelling glows red and melts. The robot is on the other side.)
ROBOT: You are an enemy of humanity. I must destroy you.
(The robot puts one claw round the man's throat, and squeezes. It turns to the safe and uses the disintegrator ray on that. The safe door vanishes and it removes an envelope.)

[UNIT Laboratory]

BRIGADIER: There was a triple security thermolock on that safe made from case-hardened Dynastreem. It was completely disintegrated.
DOCTOR: Disintegrated?
SARAH: But there's nothing that could do that. Dynastreem's indestructible.
DOCTOR: I think the Brigadier has an idea, eh, Alastair?
BRIGADIER: Anyway, the neighbours heard a commotion, but by the time the police arrived it was all over. The safe was empty.
DOCTOR: Who was this man?
BRIGADIER: Joseph Chambers, Cabinet Minister. He had certain special responsibilities in the area of security. I've been carrying out a full security check on these Think Tank people.
DOCTOR: Anything interesting?
BRIGADIER: Oh, not really. They seem to be an exemplary lot. Just one oddity. Quite a few of them were members of something called the Scientific Reform Society.
DOCTOR: Oh, really? And who might they be?
BRIGADIER: Oh, a little tin pot organisation founded years ago. It wants to reform the world on rational and scientific lines. You know the sort of thing. Harmless bunch of cranks, if you ask me. Recently
DOCTOR: Yes? Go on, then.
BRIGADIER: Well, they've had a sudden rush of new members. Quite a few well known scientists. Younger people, too. Computer technicians and so on.
SARAH: Is Miss Winters a member?
BRIGADIER: Apparently. And Jellicoe too, and quite a few of the Think Tank lot.
SARAH: Doesn't sound their style, does it.
BRIGADIER: No.
SARAH: Oh, well.
BRIGADIER: Where you off to?
SARAH: Home to bed. Busy day tomorrow. I'm still a working girl, you know.
BRIGADIER: Yes, quite right, too. You leave all this business to us.
SARAH: One thing about reform societies. They're never adverse to a bit of free publicity.
(Sarah leaves.)
BRIGADIER: Well, Doctor, what do you think
(The Doctor is lying on the work bench.)
BRIGADIER: Doctor, what are we going to do? Or shall we leave it all to Miss Smith?
DOCTOR: Let's pay a visit to Think Tank tomorrow, Brigadier. We can ask them to demonstrate Professor Kettlewell's robot. Good night.

[Kettlewell's house]

(Someone knocks on the door. Kettlewell unlocks it and looks out.)
KETTLEWELL: Hello?
(A knocking comes from somewhere else. He locks the door again.)
KETTLEWELL: Rats.
(More knocking. Kettlewell unbolts the back door and the robot enters.)
ROBOT: I, I, I
KETTLEWELL: What's the matter?
ROBOT: I have been given orders that conflict with my prime directive.
KETTLEWELL: Oh, no.
ROBOT: They say there is no conflict, yet I know there is conflict. I do not understand. Help me.

[SRS Meeting room]

SARAH: As I understand it then, Mister Short, you advocate rule by a sort of self-appointed elite.
SHORT: It's only logical. Superior types should rule, they're the best equipped for it.
SARAH: And the inferior types?
SHORT: They'd be guided, helped, kept away from harmful ideas and influences. For instance
SARAH: Do go on.
SHORT: Your own attire, is it really suitable?
SARAH: Trousers? Oh, surely that's a matter for me to decide?
SHORT: As things are at the moment, it is. But in a more rationally ordered society
SARAH: I would wear what you thought was good for me. I see. And think what you thought was good for me, too?
SHORT: It'd be for your own good.
SARAH: Oh, I see you're having a meeting here tonight. Do you think it'd be possible for me to come?
SHORT: Sorry, out of the question. Private meeting, members only. No press.
SARAH: But if I joined?
(Short's minder steps forward, arms folded.)
SHORT: I really don't think you qualify. We have very high standards.
SARAH: Oh. Well, thank you so much for your time, Mister Short, and for telling me your most interesting ideas.
SHORT: I do hope you'll include us in your article. We've been sadly misrepresented.
SARAH: Really? Well, we're covering a number of fringe organisations, and I'm sure we'll find a place for you. Somewhere between the flying saucer people and the flat Earthers.

[Think Tank]

(Hilda Winters is escorting the Doctor and Brigadier along the garden wall.)
DOCTOR: Can't thank you enough for the visit. Been most amusing.
HILDA: I suppose it all seems very elementary to a scientist of your standing, Doctor.
DOCTOR: Yes, it does rather, but never mind. You've got to start somewhere. But there is one thing I'm looking forward to. Professor Kettlewell's robot. It's in here, isn't it?

[Robotics section]

DOCTOR: Come on, then. Where's your tin man?
HILDA: I'm afraid I must disappoint you, Doctor.
DOCTOR: Oh dear. I do so hate being disappointed. I was determined to see that robot.
HILDA: We had to dismantle it.
DOCTOR: What? And such a harmless creature, too.
(The Doctor touches an area of flooring.)
HILDA: After the visit of your friend, Miss Smith, it became unstable. She introduced it to concepts it was not equipped to deal with.
DOCTOR: What, concern, compassion and useless things like that?
HILDA: We decided it would be safer to follow Professor Kettlewell's original instructions.
(The end of the Doctor's scarf sweeps the floor.)
DOCTOR: Now that is a pity. You see, one of our problems, Miss Winters, is. Oh, I say. You haven't still got the bits, have you? Maybe I could put it together again. I'm really rather good at that sort of thing.
HILDA: We have our own furnaces in the basement. The robot has been utterly destroyed.
BRIGADIER: I could get authority to search.
HILDA: You might find that difficult, Brigadier, but I won't stand on formalities. Search, by all means, if you wish.
DOCTOR: In that case, I'm sure we needn't bother. Come along, Brigadier. Miss Winters has a great deal to do.
(The Doctor opens the door to reveal Jellicoe and a young man in a white lab coat.)
JELLICOE: Miss Winters, there's a visitor. I'm sorry.
HILDA: Would you forgive me?
DOCTOR: Please, don't let us detain you.
HILDA: Philips will show you the short cut back to your car.
DOCTOR: You know, I have a feeling we shall meet again.
(Hilda and Jellicoe leave. Philips points to the far side of the room.)
DOCTOR: Come along, Brigadier.

[Think Tank]

JELLICOE: Did they believe you?
HILDA: Of course not, but it doesn't matter. But the time they can act, it will be too late.
JELLICOE: Someone from the Ministry of Health has just turned up. Apparently, under some obscure regulation they've just remembered, we have to have a complete check up on the medical records of our staff here.
HILDA: What an odd coincidence at a time like this.
(Jellicoe goes over to a young man in coat and bowler hat.)
JELLICOE: Director, this is Doctor Sullivan from the Ministry.

[UNIT Laboratory]

BRIGADIER: Did you believe them?
DOCTOR: No, of course not, and they know I didn't. And I know that they know that I didn't, and they know that I know that
BRIGADIER: Yes, all right, Doctor. All right. So where is the robot?
DOCTOR: Either it's wandered off somewhere by itself or they've hidden it.
BRIGADIER: I see. Well, I must be off. Got to try and persuade the Minister to let me raid Think Tank. What are you going to do? Oh no, don't tell me. More thinking.
(The Brigadier leaves. The telephone rings.)
DOCTOR: I beg your pardon, Brigadier. I was just thinking.
(The Doctor answers the telephone.)
DOCTOR: Yes? Yes, of course I'll talk to him. I'll talk to anybody. Professor Kettlewell? Yes, this is the Doctor.

[Kettlewell's house]

KETTLEWELL: Doctor, you've got to help me. The robot has come to my house. I've got him hidden, but he's very unstable. I may not be able to control him. We must keep him out of the hands of those Think Tank people. They've driven him almost insane! Yes, at my house. I'll be waiting at the gate.
(Kettlewell unlocks the door, and Hilda walks in with Jellicoe. At the UNIT lab, the Doctor quickly types a note and sticks it on the Tardis before leaving in Bessie.)

[Outside the UNIT Laboratory]

SARAH: Oo, I like that. What is it?
BENTON: That's promotion, Miss, to WO1.
SARAH: WO what?
BENTON: Warrant Officer. You see, technically speaking, the Brig should have a Major and a Captain under him. The UNIT budget won't run to it so they settled on promoting me.
SARAH: Congratulations. About time, too.
BENTON: Thank you.

[UNIT Laboratory]

SARAH: Doctor, I went to see those SRS people. Oh, no.
(Sarah reads the note on the Tardis.)
SARAH: Sarah, Professor Kettlewell tells me that he has the robot hidden at his house. Gone to meet him. PS it is of course possible that this message is a trap. If it is I can deal with it. PPS I am leaving this note in case I can't. Oh, the idiot! He thinks he can cope with anything.
BENTON: Right, we'd better get after him. I'll get some men.
SARAH: I'll see you there.
BENTON: Wait for us. We'll go together.

[Kettlewell's house]

DOCTOR: Professor Kettlewell? Professor Kettlewell? Professor?
(The Doctor looks out of the back door, then turns on the lights. The robot enters.)
ROBOT: You are the Doctor?
DOCTOR: How do you do? I've been so looking forward to meeting you.
ROBOT: Please confirm your identity. There must be no mistake. You are the Doctor?
DOCTOR: Yes, yes, of course.
ROBOT: You are an enemy of the human race. I must destroy you. Please do not resist. I do not wish to cause you unnecessary pain.
(The robot swings at him, and he ducks.)
DOCTOR: How very kind of you.
(The Doctor finds that the front door is now locked. He dodges the clumsy robot and throws some ball bearings on the floor before trying the back door, which is now also locked. The robot is too heavy to slip.)
DOCTOR: Prime directive. What is your prime directive?
ROBOT: I must serve humanity and never harm it.
DOCTOR: Then you mustn't harm me. I'm a friend of humanity.
(The Doctor ties his scarf between two pillars.)
ROBOT: No, you are an enemy. You must be destroyed.
(The Doctor tries swinging a chain at it then goes to the front door again. He ducks as the robot swings at him, smashing the door, and puts his hat over its 'eyes'. Then he rattles the back door knob. The robot is motionless without its sight.)
DOCTOR: Extraordinary. Extraordinary.
(The hat falls off and the robot hits the Doctor, knocking him down. He tries to crawl away but the robot advances menacingly.

Part Three

[Kettlewell's house]

(Sarah drives up and sees Bessie parked outside. She sees the hole the robot has smashed in the door and runs over to look in, then runs around the back. The robot is about to stomp on the Doctor.)
SARAH: No, no! You mustn't harm him!
ROBOT: He is an enemy of humanity.
SARAH: No, he isn't. He's a good man. A friend.
ROBOT: You were at the laboratory. You were concerned for me. You felt sorrow.
SARAH: That's right. And you refused to harm me even when you were ordered to. Those people are evil. They're lying to you. They've altered your programming to make you act all wrongly.
ROBOT: I am confused. I do not understand. I feel pain.
BENTON: Miss Smith, get down!
SARAH: No! No, don't shoot!
(But Benton does shoot, and so do the soldiers by the broken door. The robot heads for them, and smashes its way out into the yard, bullets bouncing from its metal body. Benton joins his men, and they shoot at it from all angles. The robot knocks down one soldier and continues to march away. Benson goes back inside.)
BENTON: Is he okay, Miss?
SARAH: Yes, yes, I think so.
BENTON: We just couldn't stop it.
SARAH: Oh, well, what did you have to start shooting for? He wouldn't have harmed you.
BENTON: You could have fooled me. It was trying to kill the Doctor, wasn't it?
SARAH: Yes, but that was because. Well, it doesn't matter, and it wasn't your fault, I suppose. You did your best.
BENTON: Oh, thank you very much. The US cavalry never got treated like this.
(A thud.)
SARAH: Listen.
BENTON: It's in there.
(Benton opens a metal cupboard and Kettlewell tumbles out, bound and gagged.)

[UNIT Laboratory]

(Sarah is tending to a nasty bump on the Professor's head.)
KETTLEWELL: The robot came to find me last night. It was in terrible distress. They'd just forced it to commit another crime.
SARAH: Yes, yes, I know.
KETTLEWELL: They altered his circuitry so as to overcome his prime directive. They succeeded, but at fearful cost.
SARAH: He became unbalanced.
KETTLEWELL: Yes. Then Miss Winters and Jellicoe came along while I was waiting for the Doctor. They programmed the robot to kill him. I protested, but
SARAH: Shush. Never mind, you're safe now.
KETTLEWELL: You know, when I think of that robot's potential. I invented the metal he's made of, you know. I called it living metal.
(Benton enters with a tray.)
KETTLEWELL: It actually has the capacity to grow like a living organism.
SARAH: It's quite big enough for me now, thank you.
KETTLEWELL: That's how I came to make my other discovery, you know. It's the metallic equivalent of a virus. It breaks down metal into easily recyclable form. You can see what that means, can't you? It means that we shall be able to get rid of all the metallic waste that pollutes this planet.
BENTON: Professor?
(Benson hands him a mug of tea.)
KETTLEWELL: Thank you.
(Kettlewell spots the SRS leaflet on the bench.)
KETTLEWELL: What's that doing there?
SARAH: Oh, I went to see them. Rather unpleasant.
KETTLEWELL: Scientific Reform Society. Oh yes, just before I left the Think Tank, they persuaded me to join it. I remember I went along to one of the meetings once. Very odd bunch. Didn't go there again.
SARAH: Well now, there's a meeting there tonight. Suppose you were to turn up, Professor, would they let you in?
KETTLEWELL: Very probably. I think I've still got my membership card about me somewhere.
SARAH: And if I came along too, plus my camera and tape recorder, you could smuggle me in and we could get the goods on them for the Brigadier.
BENTON: Hey, now, hang on, you two.
SARAH: What do you say, Professor, shall we try it? Of course, it could be dangerous.
KETTLEWELL: If there's anything I can do to help to defeat those people.
BENTON: But the Brigadier will go spare. So will the Doctor.
SARAH: Well, one's away and the other's asleep.
BENTON: Well, I'll go and wake the Doctor and see what he says.
SARAH: Don't you dare. He had a nasty knock on the head and he needs to rest.
BENTON: In that case, Miss, it's just not on. I'm sorry.
SARAH: Oh! Mister Benton, are we members of UNIT?
BENTON: Well, no, of course not.
SARAH: Are we under arrest?
BENTON: No, Miss.
SARAH: Well then, what we do and where we go is none of your business, is it? Come along, Professor.
BENTON: Wouldn't it be best if you
SARAH: Now just you go and blanco your rifle, or something. This way, Professor. Come on.

[Outside the SRS Meeting room]

(The Society's officials wear green uniforms, and the logo has a jagged SS look to it. The member's cards are checked very carefully.)
SHORT: Professor Kettlewell. How nice to see you again so soon.

[UNIT Laboratory]

BRIGADIER: What the blazes were you thinking of, Mister Benton? You should never have let them go.
BENTON: Well, maybe you could have stopped them, sir, but I couldn't. As the young lady pointed out, they're not really under our jurisdiction.
BRIGADIER: Bah.
BENTON: Excuse me, sir, but you did get permission to raid Think Tank?
BRIGADIER: No, Mister Benton, I did not.
(The Doctor enters.)
DOCTOR: Then you must act without it. I know what they're up to now. Worked it all out while I was having my little nap. It's all tied up with the information stolen from that poor fellow Chambers. He must have been the guardian of some kind of ultimate threat.
BRIGADIER: How on Earth
DOCTOR: I don't know exactly what it is, just the kind of thing it has to be. Well, am I right?
BRIGADIER: A few months ago, the superpowers, Russia, America and China, decided upon a plan to ensure peace. All three powers have hidden atomic missile sites. All three agreed to give details of those sites plus full operational instructions to another neutral country. In the event of trouble, that country could publish everyone's secrets and so cool things down. Well, naturally enough, the only country that could be trusted with such a role was Great Britain.
DOCTOR: Well, naturally, I mean, the rest were all foreigners.
BRIGADIER: Well, exactly. The destructor codes for firing these missiles were kept in Chambers' house in a special Dynastreem safe. The robot killed Chambers, blasted the safe open with a disintegrator gun and took the codes.
BENTON: So what can they do with them now that they've got them?
BRIGADIER: They could set off every atomic missile in the world, Mister Benton.
DOCTOR: Yes, and start a nuclear holocaust that would turn this little planet of yours into a radioactive cinder suspended in space.
BENTON: You mean he could use the information to blackmail the world? Do things our way or we light the blue touch paper.
DOCTOR: I'm afraid so.
BRIGADIER: We think they've been using this Scientific Reform Society as a front, Doctor, and I've just heard from Mister Benton here that Miss Smith and Professor Kettlewell have just gone off to try to get into one of their meetings.
DOCTOR: Kettlewell? You let Sarah go off somewhere with Kettlewell?

[Scientific Reform Society]

(Kettlewell has found the back door and unbolted it.)
KETTLEWELL: Miss Smith, are you there?
(Sarah enters.)
SARAH: How's it going, Professor?
KETTLEWELL: All right, I think. They were a bit suspicious to start with, but I found somewhere for you to hide.
SARAH: Great.

[SRS Meeting room]

(Hilda Winters is getting plenty of cheers and applause.)
HILDA: And as you know, my friends, tonight is the culmination of many years of work and planning. A brilliant and audacious scheme is about to come to its climax! (Cheers) You have all waited long and patiently during the years of scorn and ridicule. The days when we were laughed at as cranks. Well now a new and better future is almost within our grasp.
(Sarah is hidden behind some chairs and boxes, taking her photographs.)
HILDA: A future in which we, the elite, will rule as is our right! We owe it all to one man. The man whose unrivalled scientific genius has put us in the commanding position we now hold. Professor Kettlewell!
(Kettlewell gets a standing ovation as he walks onto the stage.)
HILDA: He brings with him the symbol of our movement. The creature whose intelligence and power make him a fitting emblem for our scientific new order!
(The curtains at the back of the stage part to reveal the robot. The crowd go silent.)

[Outside the SRS Meeting room]

(The Doctor is turning out his pockets. A fake pigeon, a yo-yo and other detritus are already on the desk.)
DOCTOR: Where is that pass?
(He finds a scroll.)
DOCTOR: Freedom to the city of Skaro? No. Pilot's licence for the Mars Venus rocket run. Galactic passport. Do you travel much? Honorary member of the Alpha Centauri Table Tennis Club.
(The security man gets up and advances on him, menacingly. The Doctor backs away towards the door.)
DOCTOR: Very tricky opponents, those chaps. Six arms, and of course six bats. It really keeps you on your toes. I'll tell you what, I'll just pop outside and try something
(As the Doctor goes through the door, the man falls onto his back and knocks himself out. He had been standing on the scarf.)
DOCTOR: Oh dear, I'm terribly sorry. You just like there and get some rest. I'll find help. And above all, don't worry. Everything's going to be all right.

[SRS Meeting room]

HILDA: With the aid of this robot, we shall seek out and destroy all those who try to harm us.
ROBOT: Seek out and destroy.
(The robot pushes Kettlewell aside and steps down from the stage. It sweeps the pile of boxes aside and reveals Sarah to the crowd.)
HILDA: She's a spy! Deal with her!
DOCTOR: Good evening, everyone. Now please, stay calm. Everyone keep your seat. Now then, what can I do to entertain you till my friend the Brigadier arrives? A little song? A little dance, perhaps? Not just a little dance? Anyone for cards?
(The crowd laughs.)
HILDA: Don't just stand there, you idiots, get him!
DOCTOR: Now for my next trick I shall require the assistance of a member of the audience.
(The SRS guard from outside runs at him, the Doctor ducks, and the man goes flying over him and crashes at the back of the stage. The audience love it.)
DOCTOR: I say, haven't we met somewhere before? Please, let me help you up.
(The guard and his friend twist the Doctor's arms behind his back.)
DOCTOR: Ow. Pity. Any other sporting member of the audience? Tell me one thing, Professor Kettlewell. Why?
KETTLEWELL: For years I have been trying to persuade people to stop spoiling this planet, Doctor. Now, with the help of my friends, I can make them.
DOCTOR: Aren't you forgetting that in science, as in morality, the end never justifies the means.
JELLICOE: What are we going to do with them?
HILDA: Kill them of course.
KETTLEWELL: Oh, no, no.
HILDA: They're far too dangerous to us.
KETTLEWELL: Couldn't we lock them up?
HILDA: And have them escape? It's too late to be squeamish, Professor.
DOCTOR: You see what I mean, Professor?
HILDA: Take them away.
(Gunshot!)
SARAH: Doctor!
BRIGADIER: Stay where you are! My men have this building surrounded.
(Benton covers the crowd with his rifle.)
HILDA: Where's the truck?
JELLICOE: Still outside.
HILDA: Quick. The back way.
BRIGADIER: Stop! Stay where you are.
(Hilda grabs Sarah to use as her shield. The Doctor is lying across the desk on the stage.)
KETTLEWELL: Protect us! Protect us!
(The Doctor winks at Sarah as she is dragged past him. The robot blocks the Brigadier and Benton as the bad guys leave the room.
Outside the Meeting Hall building, UNIT soldiers back away as Hilda hustles Sarah down the steps, followed by Kettlewell. When the robot appears, they start firing. Jellicoe cowers behind the robot as Kettlewell and Hilda get Sarah into the cab of a horse box. Once Short and the robot are in the back, the ramp lifts and Hilda drives through the barricade. The rest of the SRS members dash out of the rear door, followed by soldiers.)
BRIGADIER: Well, Doctor?
DOCTOR: It had to be Kettlewell. Only he could have attempted to reprogramme the robot to overcome its prime directive.
BRIGADIER: Then all that business about being knocked on the head and pushed in the cupboard
DOCTOR: Faked. Faked to gain your confidence. And they still have the destructor codes, and Sarah. And now they'll hide up somewhere and try their blackmail plan, I suppose.
BRIGADIER: But how can they? If they start a nuclear war they'll go up with the rest of us.
DOCTOR: I rather imagine that has occurred to them. You'd better find them, Brigadier, and soon.
BRIGADIER: I agree, but how?
(Benton enters with an R/T.)
BENTON: Excuse me, sir. There's a call for you from Doctor Sullivan. Linked in from HQ.
BRIGADIER: Thank you. Sullivan, are you still at Think Tank? Over.

[Think Tank]

HARRY: Yes, sir, but I may not have much time. Now listen, sir. I've managed to give them the slip and I think they've forgotten about me. They seem to be pulling out, sir. The whole place is being evacuated.

[SRS Meeting room]

BRIGADIER: Listen, Sullivan, this is urgent. Do you know where they're going? Have you any idea at all?
HARRY [OC]: Well, sir, I heard somebody mention the bunker, but it seemed to be a kind of a joke.
(Thud, crash.)
BRIGADIER: Sullivan, are you still there?

[Think Tank]

(Harry has been knocked out.)
JELLICOE: We'll take him with us. He'll be a useful hostage.
(Philips drags Harry away.)

[SKS Meeting room]

BRIGADIER: No good. Broken connection.
DOCTOR: Or broken head, if someone overheard him calling us.
BRIGADIER: He said something about them going to a bunker.

[Outside the Bunker]

(Bessie leads the convoy of Land Rovers along a track below the entrance to an underground structure.)
BRIGADIER: Well, this is the place. An atomic shelter designed and built by the Think Tank people back in the Cold War days.
DOCTOR: So if their bluff is called, they'll stay down there safe and sound and emerge to rule the survivors, if any.
BENTON: You really think they're in there, sir?
BRIGADIER: We'll soon find out. Right, Benton.
BENTON: Fall out!

[Bunker]

(UNIT are being watched.)
HILDA: Activate the automatic defence system.
KETTLEWELL: Shouldn't we talk to them first?
HILDA: We'll talk afterwards. First we must show them the strength of our position.
(Jellicoe presses a series of switches.)
HILDA: Put her with the other one.
(Sarah is dragged away.)

[Outside the Bunker]

(Through his monocular, the Doctor spots a barrel above the bunker door.)
DOCTOR: Down, Brigadier! Everyone get down!
(They all flatten themselves as machine gun fire strafes the ground in front of them.)
BRIGADIER: Get back.
(Benton and the Brigadier rejoin the Doctor at the vehicles.)
BRIGADIER: Of all the cheek. They've got troops there!
DOCTOR: I don't think so, Brigadier. Automated machine gun nest, I fancy, activated by body heat when you get within range.)
(An R/T crackles.)
DOCTOR: Shush.
BENTON: That's not me, Doctor. Someone's trying to get through on our frequency.
DOCTOR: Good man.
(Benton gets into a Land Rover.)

[Bunker]

BENTON [OC]: Greyhound Leader receiving you. Over.
HILDA: Let me speak to the Brigadier.
BRIGADIER [OC]: Lethbridge Stewart.
HILDA: Brigadier, can you hear me?
BRIGADIER [OC]: Yes, Miss Winters, I hear you. Come out and give yourselves up, or we shall attack.
HILDA: We hold two of your friends as hostages.

[Outside the Bunker]

BRIGADIER: That will not deter me. I repeat, give yourselves up or we shall attack.

[Bunker]

HILDA: You'll never reach those doors alive, Brigadier. And even if you did, you'd never get through them. By now, the governments of the world will have received our demands. Unless they are agreed to in full, the destructor codes will be used. We have associates standing by all over the world. You have thirty minutes in which to surrender.

[Outside the Bunker]

BRIGADIER: Mister Benton, take a party with grenades, find those machine gun nests, and knock them out.
BENTON: Yes, sir.
BRIGADIER: I'll show that wretched woman.

[Bunker storeroom]

(Harry is awake but tied up.)
ROBOT: Do not move. If you attempt to escape, I must destroy you.
(Sarah is brought in.)
HARRY: Oh, I say. This isn't gallant.
SARAH: James Bond. Tut.
(The man ties Sarah's ankles.)

[Outside the Bunker]

(Three concrete machine gun nests are blown up.)
BENTON: That was the lot, sir.
BRIGADIER: Right, prepare to advance.
DOCTOR: Just a moment, Brigadier.
(The Doctor takes out his sonic screwdriver and walks forward. He turn it on and a series of mines explode around the bunker entrance.)
DOCTOR: Come along then.
BENTON: Okay, move.
(They walk up to the bunker doors.)
BENTON: Shall I get some explosive, sir?
BRIGADIER: Yes.
DOCTOR: Oh, no. Must you? I really think we've had enough bangs and flashes for a bit, don't you? Hold on. Turns into a miniature sonic lance, you see.
BRIGADIER: And what do you propose to do with that?
DOCTOR: Cut out the lock for you. It shouldn't take long.
(The Doctor moves the sonic screwdriver around the area of the lock. The metal flames and melts.

[Bunker]

JELLICOE: They're getting through! It is impossible!
HILDA: Very well, we shall have to use the destructor codes. Show them we're not bluffing.
KETTLEWELL: It'll take too long to set up the sequence. They'll be in here long before that. You said we'd have plenty of time! 
HILDA: Well then, we must gain time. We shall have to use your metal friend, Professor, and this time he'd better not let us down! Is the disintegrator gun ready?
JELLICOE: Yes.
HILDA: Right. Then fit it and send him out.
(Jellicoe leaves.)
HILDA: Come along, Professor. Start getting those destructor codes operational. Maybe they'll listen when the first few missiles are fired.

[Bunker storeroom]

(Jellicoe pulls Sarah off the case she is sitting on, and opens a long thin wooden box. He takes out the weapon.)
JELLICOE: Enemies of humanity are attacking us. You must take this gun and destroy them.
(The robot grasps the weapon.)
SARAH: No! No, you mustn't!
(Jellicoe and the robot leave. Sarah and Harry struggle against their ropes.)

[Outside the Bunker]

(The bunker doors start to open.)
DOCTOR: Back. Everybody back.
BRIGADIER: They may be going to surrender.
DOCTOR: I very much doubt it. Get your men back, Brigadier, if you don't want them killed.
BRIGADIER: All right, back.
BENTON: Fall back. Fall back to the woods.
(The doors open fully to reveal the armed robot. The Land Rovers are driven into the tree line. A lone marksman takes up position and starts shooting. The robot disintegrates him.)
BRIGADIER: Well, I've brought along something that will deal with it.
DOCTOR: I very much doubt it, Brigadier.
(A tank rolls up and turns its turret towards the robot, and promptly gets atomised.)
ROBOT: Go! Go now, or I will destroy you all!

Part Four

[Bunker]

HILDA: Well, everything seems to be very satisfactory. And how are you getting on, Professor?
KETTLEWELL: I've just finished making the preliminary linkups. You don't really intend to use the destructor codes, do you?
HILDA: I want everything in readiness.
KETTLEWELL: But if they don't agree, if they call our bluff, we'll surrender, won't we?
HILDA: No. We shall fire the missiles.
KETTLEWELL: But you can't. It would mean a nuclear war.
HILDA: You want a better world, don't you? We shan't gain it without some sacrifices. Now, start the countdown, Professor.
(Kettlewell obeys, and the big 300 on the screen behind him starts counting down. 299, 298, 297, 296, 295)

[Bunker storeroom]

(Sarah is trying to untie Harry's hands.)
HARRY: How are we doing, Miss Smith?
SARAH: Okay.
HARRY: Yeah, I think it's coming.

[Bunker]

HILDA: What about food and water? How long can we hold out if the worst happens?
JELLICOE: I'm not really sure.
HILDA: Then you should be. Take me to the food storage. We must make a proper check. Keep your eye on our friends outside, Professor.
(267 and counting.)

[Bunker storeroom]

JELLICOE: Wait. What are we going to do with them?
HILDA: They're obviously no use to us as hostages. We can't afford useless mouths to feed. They'll have to be disposed of.
(Jellicoe draws his gun.)
HILDA: Later.
(Hilda and Jellicoe leave.)
HARRY: That was a near one.
SARAH: We're nearly there, I think.
HARRY: Yeah.
SARAH: Okay.
(Harry's hands are free.)

[Outside the Bunker]

BRIGADIER: What's the range and power of that weapon, Doctor?
DOCTOR: Power? Almost unlimited. Range, well, it could drill a hole in the surface of the moon.
BRIGADIER: And knock out anything we send against it.
DOCTOR: Yes. Well, it's no use staying here. Brigadier, prepare your men for an attack. Try and draw the robot away from the door. I'll slip round behind it and finish cutting the lock.
BRIGADIER: You don't stand much chance, you know.
DOCTOR: I know, but we have to try.
BRIGADIER: Right, we'll cover you as long as we can. All right, Benton?
(Benton and the Brigadier move forward with the Doctor.)

[Bunker]

(The counter is down to 87 when Kettlewell leaps up from his console.)
KETTLEWELL: Can't. I won't.
(He picks up Jellicoe's chair and is about to smash a computer.)
JELLICOE: Don't attempt to stop it!
KETTLEWELL: I can't do it! I won't do it!
JELLICOE: Let it run!
(Kettlewell backs away from Jellicoe's gun. Harry runs in and tackles Jellicoe, disarming him before knocking him out.)
KETTLEWELL: Thank heavens you've come.
SARAH: Can you cancel what you've been doing?
KETTLEWELL: There's no time. I'll punch in the hold signal.
(The countdown stops at 58.)
HARRY: Right, so now open the main doors. We're going outside.
KETTLEWELL: Yes.
SARAH: There.
HARRY: All right.

[Outside the Bunker]

DOCTOR: Wait. The doors.
(Sarah comes out with her hands up.)
DOCTOR: Sarah.
SARAH: Doctor!
(The robot turns round, and the Doctor runs over to the doors.)
SARAH: Look, please, don't shoot. We're no danger to you.
ROBOT: You must go. The soldiers must go.
SARAH: You've got to let him in there.
ROBOT: They are enemies of the human race.
SARAH: No, they're the enemies in there. They want to start an atomic war. Kill millions of people.
(The robot struggles with the conflict.)
ROBOT: You must go or I will kill. I must kill you. I must destroy you.
KETTLEWELL: No, no, he was only telling
(The robot fires the disintegrator as Kettlewell steps forward. The robot becomes distraught.)
ROBOT: I have killed the one who created me.
(The robot crashes to the ground.)
DOCTOR: Now's our chance.
(The Doctor, Harry, Sarah and the Brigadier go into the bunker. Benton takes the disintegrator gun from the robot and follows them.)

[Bunker]

(Hilda finds Jellicoe still unconscious on the floor, and sees UNIT coming along a corridor on a CCTV monitor. She picks up a folder, sits at Kettlewell's console and restarts the countdown.)
BRIGADIER: Get away from that keyboard.
HILDA: You won't shoot, Brigadier.
(Sarah picks up Jellicoe's gun.)
SARAH: Maybe he won't, but I will. Move away!
HILDA: Why not? It's finished. The firing instructions have gone out.
BRIGADIER: I can still get the major powers to use their fail-safe procedures.
HILDA: Too late, Brigadier.
BRIGADIER: Cancel the destructor codes!
HILDA: When that reaches zero, the missiles will be fired, and no one can send the cancel codes in time.)
(27, 26, 25, the Doctor runs to the console.)
DOCTOR: She may be right, Brigadier.
BRIGADIER: Benton, get them both out of here.
BENTON: Miss Winters.
(Benton grabs Jellicoe.)
BENTON: Move!
(Benton, Hilda and Jellicoe leave. 17, 16)
DOCTOR: The trouble with computers, of course, is that they're very sophisticated idiots. They do exactly what you tell them at amazing speed, even if you order them to kill you. So if you do happen to change your mind, it's very difficult to stop them obeying the original order, but
(2) 
DOCTOR: Not impossible.
HARRY: Congratulations, Doctor.
SARAH: You've done it!
BENTON: Well done, Doctor.
(Sarah remembers something, and leaves.)
BRIGADIER: Right, that's over. Now for a little mopping up.
BENTON: Right, sir.
(In a bunker corridor, Sarah nearly walks into the robot.)

[Outside the Bunker]

BRIGADIER: Vanished? How can they have vanished?
BENTON: We were all pretty busy inside, sir, mopping up the rest of that Think Tank lot. We noticed the robot was gone when we came out and everyone assumed that someone else had got it.
DOCTOR: And Sarah?
BENTON: Well, we thought, we thought she'd gone home.
DOCTOR: Gone home? You mean not one of you connected the disappearance of Sarah with the vanishing of the robot?
BRIGADIER: You're sure there is a connection?
DOCTOR: I think so. Don't you?
HARRY: Why Sarah?
DOCTOR: The robot killed Kettlewell, remember, the man who created it. It must be in a state of tremendous emotional shock. What more natural than it should turn to the one person who ever showed it kindness?
BRIGADIER: Hmm. Keep looking, Benton.
BENTON: Right, sir.

[Bunker storeroom]

SARAH: Honestly, they're bound to find us.
ROBOT: Anyone who finds us will be destroyed.
SARAH: Why? What's the point of more killing? I keep telling you, it's all over. What can you do alone?
ROBOT: I can bring about the destruction of humanity. But do not fear, Sarah. You alone will be saved.
(The robot turns and beeps a lot.)
ROBOT: The bunker is cleared. Come.

[Outside the Bunker]

BRIGADIER: Well?
BENTON: Still nothing, sir. We're spreading the search radius wider and wider, but the bigger the area to cover the harder it gets.
DOCTOR: There is just one teeny weeny little thing.
BRIGADIER: What's that?
DOCTOR: Something else you haven't thought of. What are we going to do with it when we find it?
BRIGADIER: Yes. You know, just once I'd like to meet an alien menace that wasn't immune to bullets.
BENTON: Excuse me, sir.
BRIGADIER: Hmm?
BENTON: Well, when Professor Kettlewell was here talking to Miss Smith, he said the robot was made of some kind of living metal. He even said it could grow.
DOCTOR: Did he now.
BENTON: Yes, and he went on about some kind of metal virus. Something that attacked the living metal.
DOCTOR: The same way that disease attacks animal tissue.
BENTON: Well, something like that. Anyway, I just wondered. If we could
DOCTOR: Yes?
BENTON: Oh, I'm sorry. It was probably a daft idea anyway.
DOCTOR: Wonderful, Mister Benton. Wonderful! Brigadier, I must get to Kettlewell's place at once. You find the robot.
BRIGADIER: You'd better go with him.
HARRY: Right, sir.
BRIGADIER: Keep in R/T contact!

[Bunker corridor]

(The robot and Sarah meet a UNIT soldier.)
SARAH: No! Don't hurt him. Let him go. He's not important enough. (to the soldier) Don't shoot. Just leave now. Don't worry about me, just go.
(The soldier gets past the robot and flees.)

[Outside the Bunker]

BENTON: Look, sir.
(The soldier comes running out.

[Bunker]

(The robot moves the control for the main doors then turns to the countdown. It resets it to 300 and starts it running again.)
SARAH: No! No! Why? Why?
ROBOT: I destroyed Kettlewell. I must see that his plan does not fail.
SARAH: But he changed his mind. He wouldn't want you to continue.
ROBOT: Mankind is not worthy to survive. Once it is destroyed, I shall build more machines like myself. Machines do not lie.

[Kettlewell's house]

(The Doctor is searching Kettlewell's papers.)
DOCTOR: Why didn't that silly man write up his experiments properly?
(The Doctor starts mixing the contents of various test tubes.)
BRIGADIER [OC]: Doctor, this is the Brigadier. Can you hear me?
HARRY: (into R/T) This is Lieutenant Sullivan, sir. The Doctor's rather busy at the moment.
DOCTOR: Tell him to stop pestering me. I've found a metal virus and I'm trying to prepare an active solution, but he must give me time.

[Outside the Bunker]

BRIGADIER: Sullivan, tell the Doctor we've found the robot.
HARRY [OC]: Well done, sir. Where is it?
BRIGADIER: It's shut itself inside the bunker with Miss Smith.

[Kettlewell's house]

DOCTOR: What? Yes. Yes, of course. Suppressed Oedipus complex leading to excessive guilt and overcompensation.
BRIGADIER [OC]: Doctor, Oedipus is not
DOCTOR: Brigadier, the robot will try to carry out Kettlewell's plan. Is the computer terminal in the bunker still active?
BRIGADIER [OC]: Far as I know. I don't suppose anyone thought to
DOCTOR: Can you switch off the electricity supply?
BRIGADIER [OC]: Yes. No, no, it's on a special sealed circuit.
DOCTOR: Then warn all the major powers. The emergency is not over. They must operate full fail-safe procedures at once.

[Bunker]

(19, 18, 17. Sarah is terrified. 10, 9, 8 then the monitor flashes up Fail Safe Countdown Aborted.)
SARAH: You see? They've operated the fail-safe mechanism. Give up now. Please!
ROBOT: Humanity must be destroyed. It is evil, corrupt.
SARAH: But you can't take on the whole world. Don't you understand? They'll destroy you!
ROBOT: Do not fear. I cannot be destroyed.
(The robot unlocks the main doors.)
ROBOT: Come.

[Kettlewell's house]

DOCTOR: Come along, man, come along.
(Harry finds a metal bar.)
HARRY: This any good?
(The Doctor tests it with a magnet, then loads a pipette with his bubbling orange solution and squirts some onto the bar.)
DOCTOR: We've done it, Harry. We've done it!

[Outside the Bunker]

BENTON: Sir.
(The robot comes out of the bunker, followed by Sarah.)
BRIGADIER: No one's to open fire. She may find a chance to get clear.
ROBOT: Stay here.
(Sarah nods. The robot turns towards UNIT.)
BENTON: It's going to attack, sir. Shall we pull back?
(The Brigadier spots something in the back of the Land Rover.)
BRIGADIER: Of course. The very thing.
(He picks up the disintegrator gun.)
BRIGADIER: I think just for once, we're not going to need the Doctor.
(The Brigadier fires the gun at the robot. It staggers and glows, then starts to grow!
BENTON: (silent) What?
(Sarah makes a dash for it but trips, and becomes Fay Wray to the robot's King Kong as it gently puts a claw around her waist and lifts her up.)
BRIGADIER: Follow me and hold your fire until ordered.

[Think Tank]

(The robot deposits Sarah on the roof of Think Tank. She grabs for a chimney stack.)
ROBOT: You will be safe. See how I deal with our enemies.
BRIGADIER: She's out of the line of fire. Launch your grenades.
BENTON: Smith, Hampton, get down here quickly with the launcher. Fire!
(The one-sided battle starts as Bessie hurtles along the road. The robot picks up two soldiers and drops them into the car park.)
BRIGADIER: Right, pull back!
(Another soldier gets stomped on as the rest return to the Land Rovers. Huts are crushed underfoot by the robot as it follows the fleeing UNIT vehicles and men through the complex. Then the Doctor and Harry arrive in Bessie.)
HARRY: Curiouser and curiouser.
DOCTOR: Said Alice.
HARRY: Exactly.
(The robot starts to return to Sarah, walking into electricity cables and swatting the irritants aside. The Doctor joins UNIT.)
DOCTOR: I see our little problem seems to have grown. Where's Sarah?
BENTON: She's safe enough, Doc.
BRIGADIER: I gave it a blast with the disintegrator gun.
BENTON: It left her up on the roof.
DOCTOR: Really, Brigadier, you should be more careful with your little toys. You've given it just the infusion of energy it needed.
BRIGADIER: Well, I've sent for the artillery, and the RAF are on their way.
DOCTOR: I hope that won't be necessary.
BRIGADIER: What on Earth is that?
(That is a bucket bubbling over with orange gunk.)
DOCTOR: Another piece of brilliance from the late Professor Kettlewell, and one that will solve our problem, I hope. Drive on, Harry.
HARRY: Right, Doctor.
DOCTOR: Wish me luck, Brigadier.
(Bessie drives off.)
BRIGADIER: Now just a moment, Doctor!
SARAH [OC]: Hey! Hey, get me down!
BRIGADIER: Don't just stand there, Benton. Go and help Miss Smith.
BENTON: Right, sir.
(The robot stands and watches as the little yellow car zooms up and past him. The Doctor throws the contents of the bucket over its ankles and shins. The orange quickly spreads down to its feet and then upwards as Bessie returns to the UNIT vehicles.)
BRIGADIER: What was that stuff?
DOCTOR: Some of Kettlewell's metal virus in an active solution.
BRIGADIER: Will it work now the thing's that size?
DOCTOR: Oh, even faster, I hope. Look.
(The robot is a vivid orange and starting to gurgle as it shrinks.)
DOCTOR: It's thrown the growth mechanism into reverse.
HARRY: Oh, well done, Doctor.
DOCTOR: Thank you, Harry.
(The robot returns to its normal size, then falls backwards onto the ground. The Brigadier, the Doctor and Harry walk forward to inspect it. The robot is about four feet long now.)
BRIGADIER: I'll have it taken away. Broken up, just in case.
DOCTOR: No. No, Brigadier, that won't be necessary. Look.
(The robot dissolves away into nothing.)

[UNIT Laboratory]

(Sarah is staring at nothing when the Doctor enters.)
DOCTOR: Sarah? Sarah?
(He takes a paper bag out of his pocket.)
DOCTOR: Would you like a jelly baby? I had to do it, you know.
SARAH: Yes, yes, I know. It was insane and it did terrible things, but, but at first, it was so human.
DOCTOR: It was a wonderful creature, capable of great good, and great evil. Yes, I think you could say it was human. You know, what you need is a change. How about a little trip in a Tardis. I'm just off.
SARAH: Wait, you can't just go.
DOCTOR: Why not? It's a free cosmos.
SARAH: The Brigadier
DOCTOR: The Brigadier wants me to address the Cabinet, have lunch at Downing Street, dinner at the Palace, and write seventeen reports in triplicate. Well, I won't do it. I won't, I won't, I won't.
(The Doctor hits a hapless brick sitting on the workbench. That hurts.)
DOCTOR: Why should I?
SARAH: Doctor, you're being childish.
DOCTOR: Well of course I am. There's no point in being grown up if you can't be childish sometimes. Are you coming?
(Sarah takes a jelly baby and they both laugh. The Doctor unlocks the Tardis as Harry enters.)
HARRY: Hello. Well, what are you two up to now, eh?
DOCTOR: We're just going on a little trip. Would you like a jelly baby?
HARRY: (taking one) Little trip? What, in that old police box?
DOCTOR: Yes, as a matter of fact, in that old police box.
(The Doctor snatches back the sweet.)
HARRY: Oh, come along now, Doctor. We're both reasonable men. Now, we both know that police boxes don't go careering around all over the place.
DOCTOR: Do we?
HARRY: Of course we do. The whole idea's absurd.
DOCTOR: Is it? You wouldn't like to step inside a moment? Just to demonstrate that it is all an illusion.
HARRY: Well, if you think it'll do any good.
DOCTOR: Oh, yes, it'll make me feel a lot better.
SARAH: Doctor.
DOCTOR: In you go.
HARRY: Right-o.
(Harry enters the Tardis.)
HARRY [OC]: Oh, I say!
(Sarah and the Doctor enter the Tardis and it dematerialises.)
BRIGADIER: Doctor, about that dinner at the Palace. Her Majesty. Yes, well, I'll tell them you'll be a little late.