[Learning Hall]

(A man in hi-tech clothing removes a tablet from a hole in the wall and makes an announcement.)
SELRIS: Class three one nine six in the first grade. The names of the first selected candidates are, male, Abu-Gond! The second name is female. Vana-Gond!
THARA: (a young man) No!
SELRIS: Abu-Gond and Vana-Gond, alone of your generation you have been chosen to receive the highest honour that can befall a Gond. You are now the companions of the Krotons! Our warmest, our most sincere congratulations to you both. You will now step forward for the investiture of your robes of honour. Eelek.
(Eelek, played by Philip Madoc, places a silver cape on Abu's shoulder.)
VANA: Please, Thara!
THARA: You can't go. I won't let you go!
VANA: I must!
THARA: Look, Vana, we can run away. There's still time.
VANA: You know that's not possible. We must always obey.
THARA: Why?
SELRIS: Because, my son, it is the law of the Krotons!
(A hexagonal door in the wall opens, and Abu walks through, proudly.)

[Planet surface]

(The Tardis materialises at the base of a cliff. The Doctor, Zoe and Jamie look around at the bleak landscape.)
DOCTOR: Lovely, lovely, lovely.
JAMIE: Pwoar, bad eggs. Let's try somewhere else.
ZOE: No, wait a minute. Where are we?
JAMIE: You don't expect him to know, do you?
DOCTOR: Well, let's explore shall we?
(The Doctor puts up an umbrella.)
JAMIE: An umbrella?
DOCTOR: Yes, twin suns. It's bound to be hot.
JAMIE: Oh.
ZOE: I don't think I like it here. It looks dead.
JAMIE: Aye, it smells dead.
ZOE: Sulphur, isn't it? It could be poisonous.
DOCTOR: No, no, no, no, the instruments in the Tardis would have told us. No it's a, it's a mixture of ozone and sulphur. Very bracing!

[Cliff path]

(They clamber up the side of the cliff. The Doctor picks up a flat rock.)
JAMIE: What's that?
DOCTOR: Oh, fascinating structures. Magnesium silicate.
JAMIE: Eh?
ZOE: He means mica.
JAMIE: Oh. What? (They reach the top.)
DOCTOR: Dead, is it?
(They look down on an alien town of large buildings made of triangles.)
ZOE: Is it a city?
DOCTOR: Yes, fascinating architecture. It's more typical of a low gravity planet, and yet I think this is quite normal. Yes.
ZOE: Inca, perhaps?
DOCTOR: Yes, possibly.
JAMIE [OC]: Doctor!
DOCTOR: Come on, let's see what he's up to. Be careful.
(Jamie is making his way down a scree slope.)
JAMIE: Doctor, down here.
JAMIE: Doctor, down here!

[Outside the Dynatrope]

(Jamie has led them to a large metal structure in another cliff face with a hexagonal door and ramp leading up to it.)
ZOE: What is it?
JAMIE: I don't know. There's a ramp here.
ZOE: Yes, and there's a door as well. Is it a wall?
DOCTOR: I hardly think so, Zoe.
JAMIE: Phwoar, that smell's a lot stronger round here.
DOCTOR: Oh this is interesting!
ZOE: What, Doctor?
JAMIE: Oh, metal, isn't it?
ZOE: What, covered in moss and lichen?
JAMIE: Well, er.
DOCTOR: Metal? Would you say so? I think we'd better get away from here.
JAMIE: What?
DOCTOR: Come along.
ZOE: But why?
DOCTOR: Well, this isn't a building, this is a machine. Come along.
JAMIE: Machine? Doctor, it's opening!
DOCTOR: Come on, quickly. Behind the rocks. (The Doctor, Jamie and Zoe hide behind a convenient boulder and watch Abu totter out, somewhat dazed but still wearing his cape. Two nozzles emerge from either side of the door.)
JAMIE: What's the matter with him?
DOCTOR: Shush!
(Abu is enveloped in opaque gas. He collapses, groaning. When the gas clears, all that is left is his metal breastplate and its curled wire necklace.)
ZOE: Oh, that poor man.
JAMIE: What happened to him?
DOCTOR: I don't know, Jamie. Come on, let's get away from here.

[Learning Hall]

THARA: Can't you give the order she doesn't have to go? You're our leader!
SELRIS: But the Krotons have chosen Vana. It is a great honour!
THARA: Honour? Why do we take their orders?
EELEK: Vana.
THARA: We don't even know if they exist.
VANA: Thara, you can't say things like that.
EELEK: Get out of the way.
THARA: She's not going into that machine!
EELEK: She has to go in. No one defies the Krotons.
THARA: All right!
(Thara draws a small metal hand weapon, a metal axe.)
EELEK: Now don't be so stupid!
SELRIS: Thara!
EELEK: Disarm him!
(Thara pulls Vana behind him.)
THARA: Keep back!
(Meanwhile the Doctor, Jamie and Zoe are coming down a stone staircase.)
ZOE: Oh, I hope they're friendly.
DOCTOR: Now just leave this to me, Zoe.
(The Doctor steps down into the hall.)
DOCTOR: We are friends!
(Wicked looking spears are pointed at his throat.)
DOCTOR: It's all right. Now don't be afraid.
JAMIE: We have trouble.
AXUS: Who are you?
DOCTOR: But, but, one of your people has been
AXUS: You're strangers. Where are you from?
ZOE: Well, if we told you it wouldn't mean anything.
AXUS: Answer me. Where are you from?
DOCTOR: There's no time for explanations! As I say, one of your people has been
AXUS: They're not Gonds! Their clothes, the way they're dressed.
DOCTOR: Look, we are friendly.
JAMIE: Look, are you going to let us pass or not?
ZOE: Doctor! Look.
EELEK: Do something about him. He's your son.
THARA: I'm warning you. One step nearer.
SELRIS: Thara, will you be reasonable? The Krotons have sent for Vana.
THARA: She'd not going. Nobody comes back from there!
VANA: Let me go, Thara. Please. I don't want them to hurt you. (With a spear point at his throat, Thara throws down his weapon. Vana steps forward to Eelek, who puts a curly necklace with a breastplate attached around Vana's neck.)
EELEK: A bit of sense, just in time.
ZOE: That doorway. It's like the other one.
JAMIE: Aye, and she's wearing a cloak just like that chap we saw killed.
ZOE: Is she being sacrificed?
DOCTOR: Oh, I don't think so, Zoe. They're too civilised for that.
JAMIE: Can we not stop them?
DOCTOR: Well, we can try. Just a minute. Wait!
AXUS: They're interrupting the ceremony! Take them!
JAMIE: Now just. (guards grab them) Aye, you wouldn't be so tough without these guards round you.
AXUS: Get back. I accept your challenge.
JAMIE: Oh you do, do you? Aye, well, that's just fine with me then.
DOCTOR: Now Jamie, don't be so rash.
JAMIE: Ah don't worry, Doctor. I'll see to this laddie.
(A guard offers Jamie an axe.)
JAMIE: No, I'll not be needing that, thank you.
ZOE: Oh, Jamie, watch out!
(Axus swings his axe and Jamie dodges easily.)
DOCTOR: Jamie!
(Axus grabs Jamie's arm and they come in close for a trial of strength.)
ZOE: Oh Doctor! Oh, can't we stop them? Oh, Jamie.
(The axe moves closes to Jamie's head.)
ZOE: Oh Jamie, come on!
(Jamie forces Axus' arm back over his shoulder and he drops the axe before falling to the floor clutching his wrist. Jamie rejoins the Doctor and Zoe.)
ZOE: Doctor, look. The girl!
(Vana looks back at Thara then walks through the doorway.)
SELRIS: What is happening? Who are these people? 
DOCTOR: That was the very question I was going to ask you! What is happening here? Where has that girl gone?
AXUS: Eelek, they forced their way through!
SELRIS: Who are you?
DOCTOR: There is no time to explain!
JAMIE: Look, you wouldn't believe us even if we told you.
ZOE: We're from another planet, another world.
DOCTOR: That girl. Now where has she gone?
SELRIS: How can they be from another planet?
JAMIE: Och, look, we're just wasting time. Now where has she gone?
DOCTOR: What's behind that wall?
THARA: The Krotons. They've sent her to join the Krotons.
ZOE: Well, what are the Krotons?
THARA: The Krotons live in the machine, so we're told.
SELRIS: Vana is joining the Krotons. It is a great honour.
THARA: Honour? She didn't want to go. Nobody really wants to disappear into that thing.
(The Doctor takes a closer look at the door.)
DOCTOR: How do you open this door?
EELEK: Why are you asking so many questions?
DOCTOR: Because a moment ago we saw a young man dressed in a silver robe just like that girl. We saw him killed!
SELRIS: Abu-Gond?
EELEK: That's ridiculous. How can these people have seen Abu-Gond?
SELRIS: He's with the Krotons.
JAMIE: Aye, well, we saw someone killed anyway. He came out of that machine and was
ZOE: Vapourised.
JAMIE: Aye. Right round the other side.
AXUS: Other side?
SELRIS: You have been in the wasteland.
EELEK: They're contaminated. You're contaminated. No one goes into the wasteland.
ZOE: Why not?
EELEK: Because it's poisoned, and you will die.
DOCTOR: Well, it may have been poisoned once, but I can assure you it's quite safe now.
JAMIE: Doctor, that girl. If she comes out that way.
DOCTOR: Oh Jamie, you're right. We must save her!
JAMIE: I know!
DOCTOR: Well, come on!
JAMIE: That's what I'm saying!
SELRIS: Where are you going?
ZOE: To the wasteland!
(The Doctor, Jamie and Zoe run out.)
SELRIS: But you can't. It's against the law of the Krotons!
THARA: I'm going with them!
SELRIS: Thara, come back! 
THARA: If they can go into the wasteland, I can.
SELRIS: Thara! You'll die!

[Outside the Dynatrope]

JAMIE: There it is.
DOCTOR: I wonder how long. I imagine we haven't much time.
ZOE: What are you going to do?
(The Doctor picks up a piece of mica.)
DOCTOR: You keep away, Zoe. Keep right away.
THARA: Can I help?
DOCTOR: Well, Mister?
THARA: Thara.
DOCTOR: Yes, well you can find some more stones like this.
THARA: What?
DOCTOR: Well, if you want to help! Now then.
(The Doctor uses his umbrella to force the stone into the right hand nozzle.)
DOCTOR: Yes, that one.
(The Doctor takes a stone from Thara and forces it into the other nozzle.)
DOCTOR: Right! Come down here.
(The group hides. The door opens.)
ZOE: Doctor, I think I can hear something.
DOCTOR: Yes Zoe, so can I.
(Vana stumbles out of the doorway.)
THARA: Vana!
JAMIE: Keep down!
(The Doctor runs forward to catch Vana, with his open umbrella shielding them from the door nozzles.)
ZOE: Oh Doctor, quick!
JAMIE: Doctor, look out!
ZOE: Oh Doctor, hurry!
JAMIE: Quick!
(The Doctor carries Vana to their hiding place. The stones are finally pushed from the nozzles and the deadly gas is expelled onto empty air.)
THARA: What's happened? What have they done to her?
(Some of the gas has caught the umbrella, and ruined it.)
DOCTOR: The vandals. Look at that.
ZOE: That could have happened to you!
DOCTOR: My favourite umbrella.
THARA: She doesn't know me. She can't speak or anything.
JAMIE: Aye, it's something that those Krotons have done to her.
DOCTOR: Let me see. Oh dear, this is almost catatonic. ZOE: Isn't there anything you can do?
DOCTOR: I'm not a Doctor of medicine you know, Zoe. However, if there's no damage to the tissue. Is there anywhere we can take her?
THARA: My father's house is quite near, on the edge of the community.
DOCTOR: Well, let's take her there. Give me a hand. Come on, Jamie.

[Selris' house]

(A simple wattle and daub place with a curtain for a door. Selris gives Zoe a clay beaker and she takes a small sip.)
SELRIS: It's almost impossible to believe. The Krotons have always been our good friends. Our benefactors.
ZOE: Well, you've only got to see what they've done to Vana.
SELRIS: Yes, poor child.
JAMIE: How is she?
THARA: Just the same.
(Thara leaves.)
(The Doctor is swinging his pocket watch in front of Vana's eyes.)
DOCTOR: You're resting. You're calmly resting. Your mind is quite empty. You're resting. Now, you're going to sleep, Vana. Sleep. Feeling sleepy. Very sleepy. Sleep.
(Vana's eyes close.)
SELRIS: You see, every so often the two best of our students have entered the machine to join the Krotons. They can't all have been murdered.
ZOE: Well, it's possible. If they had you wouldn't know because this spray stuff just
JAMIE: Dissolves everything. In any case, none of your people ever go into the wasteland.
SELRIS: But why should they do it? Why should they kill the best of our students?
ZOE: What are they like, these Krotons?
SELRIS: No living person has ever seen them. They never come out of the machine.
ZOE: Never?
SELRIS: Not since the beginning. Not for thousands of years.
ZOE: How is she?
DOCTOR: She's asleep at last.
JAMIE: Is she going to be all right, though?
DOCTOR: Well, I hope so, Jamie. It's difficult to tell.
(Selris hands the Doctor a beaker.)
DOCTOR: Thank you.
SELRIS: And she was one of the finest students we've ever produced.
DOCTOR: Oh really? Competition for you, Zoe.
ZOE: Selris was just saying that no one's ever seen these Krotons.
JAMIE: Aye, they never leave that machine.
DOCTOR: How did all this begin, Selris?
SELRIS: According to our legends, silver men came out of the sky and built a house among us. The Gonds attacked them but the silver men caused a poisonous rain to fall, killing hundreds of our people and turning the earth black.
JAMIE: The wasteland.
SELRIS: Yes. Because it was said that ever afterwards anyone who set foot there would die in terrible pain.

[Learning Hall]

(A balding man with a torch comes down to check the learning machines. He is grabbed by four young men.)
CUSTODIAN: Who are you? What do you want? Leave me alone!
THARA: The Krotons. You must know a lot about them.
CUSTODIAN: What do you mean?
STUDENT: You're their servant, aren't you? You work for them.
CUSTODIAN: I am only the Custodian of the Learning Hall.
THARA: Of course. So you can tell us what we want to know.
CUSTODIAN: I am forbidden to discuss the secrets.
STUDENT: We only want to know how to get at them.
THARA: We want to see the Krotons for ourselves.
CUSTODIAN: Nobody has seen the Krotons, not for thousands of years.
THARA: You're sure they don't come out of the machine in the darkness when there's no one here?
CUSTODIAN: No. Come out? Never!
THARA: Then how do they give their orders? Answer me!
CUSTODIAN: There are messages. You must know that.
THARA: What else?
CUSTODIAN: Sometimes there is a voice.
THARA: But you've never seen them? There's no way you can get inside there?
CUSTODIAN: Only the companions of the Krotons may enter.
THARA: And now we know what happens to them. But you can summon the Krotons, can't you?
CUSTODIAN: It is not for me to summon them. I obey their commands.
THARA: If we can't get in there, then we must fetch them out. Their precious teaching machines. Smash them!
CUSTODIAN: Smash the machines? Guards!
(The boys put their hands over his mouth, and the Student threatens with his axe.)
THARA: Do not hurt him! Tie his hands and gag him.
STUDENT: Well, keep still then. We've no quarrel with you.

[Selris' house]

JAMIE: But what happened after this war with the Krotons?
SELRIS: Ever since, we have lived in peace with them. The Krotons never show themselves to us, but we learn from them through the teaching machines.
ZOE: Teaching machines?
SELRIS: Yes, in the Hall of Learning, where you were today. The machines fill the mind with knowledge.
DOCTOR: And everyone uses these machines?
SELRIS: When they are young, yes. That is the law.
DOCTOR: Whose law, Selris?
SELRIS: Our law. The Gonds'.
DOCTOR: But I thought you said all your laws were given you by the Krotons?
SELRIS: Yes, all our science, all our culture, everything we have, has come from the machine.
DOCTOR: I see. A sort of self-perpetuating slavery. And the Krotons always choose your two most promising students?
SELRIS: To be their companions, yes. Do you think they've all been killed?
JAMIE: Aye, well, we saw one of them killed anyway.
ZOE: Well why are they doing it, Doctor? What's the point?
DOCTOR: Hmm? Well, it's time it was stopped, anyway. It's high time it was stopped.
SELRIS: What shall I tell my people? How can I explain?
JAMIE: Explain what? Just tell the truth.
SELRIS: What, that they've been tricked? That for thousands of years the best of our students have been dying, murdered by the Krotons?
ZOE: Well, what are you afraid of?
DOCTOR: Another war between your people and the Krotons, you mean.
SELRIS: Yes. There could be terrible bloodshed. Another wasteland here in our community.
(A man enters.)
BETA: Selris.
SELRIS: Ah, Beta. Come and meet our guests. My friends, this is Beta, our controller of Science and my son's good friend.
BETA: That's what I'm here for. Do you know what Thara's planning?
SELRIS: Planning?
BETA: He and some students gone out to the Learning Hall. They're going to wreck the machines.
SELRIS: No!
BETA: You've got to stop them, Selris. I came as quickly as I could, but they'll be there by now.
SELRIS: Then it's too late!
DOCTOR: Not if we cut through the wasteland.
JAMIE: Aye, it's the shortest route.
SELRIS: The wasteland?
BETA: But the poison?
DOCTOR: Oh, that wore off a long time ago. It's quite safe now.
JAMIE: Oh well, look, we've been in it twice today and we're all right.
SELRIS: Very well.

[Learning Hall]

(Thara strikes the first blow with his axe.)
THARA: Come on!
(The other boys join in the destruction. Somewhere a machine comes to a conclusion and an X appears on a monitor. An alarm sounds and X comes up on other screens.)
THARA: There! That should fetch them out!
STUDENT: Come on, let's wreck another!
THARA: Smash them!
COMPUTER [OC]: Stop! This is a warning. Leave the hall. All Gonds leave the hall now.
STUDENT: It's the Krotons!
COMPUTER [OC]: Leave the hall. All Gonds leave the hall now.
THARA: That's just a voice. Listen.
COMPUTER [OC]: This is a warning.
THARA: Come out, you Krotons, and fight! Come out!
STUDENT: Murderers!
(The boys start hitting another machine as Jamie and Selris run in followed by the Doctor, Beta, Jamie and Zoe.)
SELRIS: Stop!
THARA: Leave me alone!
SELRIS: What are you doing?
(Selris pulls Thara off the machine.)
DOCTOR: Stop it. Stop it, all of you! Listen to me. This will do no good at all. These Krotons must have enormous scientific powers. You can't defeat them with axes!
(The Doctor is being watched on a monitor. A metal pole with a box on top moves across to another monitor where a pixilated image of the Doctor appears.)
DOCTOR: Now, if this was an atomic laser, it might be more use.
THARA: An atomic-laser? Is that better than an axe?
SELRIS: Look at the damage you've done. Completely senseless.
THARA: Look what they did to our friends, Father. 
SELRIS: Destroying the machines won't avenge Abu, or help Vana, will it?
STUDENT: But we can't get in there! If we attack their machines
THARA: The Krotons will come out.
DOCTOR: I think something's coming out now.
(A small round hatch opens to the left of the door and a light on a long flexible neck pokes out like a metallic snake.)
ZOE: What is it?
DOCTOR: I don't know, Zoe, but keep well clear of it.
(Blinking, the thing stretches out further into the hall.)
JAMIE: Look out!
THARA: What's it doing?
ZOE: It seems to be looking at us.
JAMIE: How can it be? It's not alive, is it?
(The box on a pole turns to show us the picture of the Doctor on its screen.)
ZOE: Doctor, it's after you.
(The Doctor backs away, falling over debris, as the probe gets in very close to his face.)

Episode Two

[Learning Hall]

(The Doctor puts his hands up in front of his face, and the probe starts to swing around, searching. He crawls away, keeping his back to it.)
ZOE: Oh Doctor, don't move!
DOCTOR: It's all right, Zoe. I think it's quite safe now.
JAMIE: Oh, I wouldn't be so sure.
DOCTOR: Just watch this, Jamie.
(The Doctor walks towards the probe, still holding his hands out in front of his face. Suddenly he drops them, and the probe swings towards him, then he raises them again and it resumes its search.)
ZOE: Pattern recognition.
DOCTOR: Yes, and the pattern is my face.
SELRIS: Doctor, do you mean that thing was sent out to attack you and only you?
DOCTOR: Yes, so it seems. It's rather flattering, isn't it.
ZOE: Well then, the Krotons know who you are.
JAMIE: Aye!
ZOE: Or at least what you look like.
DOCTOR: Yes. That means they must have a scanner in the wall of the machine. Now if we can find that, we might be able to get in touch with them.
JAMIE: Doctor!
(The Doctor has lowered his hands to talk to his companions and the probe is about to strike. Everyone scatters. A student tries to sneak up behind the probe with an axe, and gets a dose of the disintegrating gas for his efforts. An ashy outline and his axe are all that remains.)
JAMIE: Oh, no.
(The computer removes the Doctor's image from its screen and the probe retreats back through its hole in the wall.)
JAMIE: It's gone back.
DOCTOR: Yes. That poor fellow must have confused it's attack mechanism.
JAMIE: Eh?
DOCTOR: Well, it was programmed to kill once. Me! It must think that it's succeeded, stupid machine.
THARA: There's your wonderful Krotons for you Father! Murderers!
(Thara throws the student's axe at the door.)
SELRIS: No! Thara, don't provoke them!
THARA: Is that all you care about, not provoking them?
SELRIS: What can we do against their weapons?
THARA: We can fight!
COMPUTER [OC]: This is a warning. Your leader has been destroyed. All Gonds leave the Learning Hall at once. At once.
THARA: No! Stay and fight!
COMPUTER [OC]: Leave the Learning Hall. All Gonds leave the learning hall.
SELRIS: Everyone, leave the hall. Now!

[Selris' house]  

(Vana is lying with her eyes open as the Doctor examines her with a bright light.)
ZOE: Where did this come from?
DOCTOR: I borrowed it from Beta.
ZOE: But I thought they didn't know anything about electricity?
DOCTOR: They don't. That works on stored solar energy. Yes, the Gonds are quite advanced in some ways. Their medicine's very good, but they haven't got much general chemistry. I wish they had an ETC machine though.
ZOE: Yes. There are tremendous gaps in their knowledge. Well, they only seem to know what the machines teach them.
DOCTOR: Yes. And the machines are programmed by the Krotons, so the gaps in their knowledge may be significant. Ah, Selris.
SELRIS: How is she, Doctor?
DOCTOR: Well I think she's better. It's difficult to tell. Selris, is it safe to enter the Learning Hall yet?
SELRIS: Why?
DOCTOR: Zoe and I want to have a look round, don't we, Zoe?
ZOE: Oh, do we?
DOCTOR: Yes, that's right. Jamie, hold out your hand, will you?
JAMIE: What for?
DOCTOR: These pills I got from Beta.
JAMIE: There's nothing wrong with me.
DOCTOR: No, no. They're for Vana. I want you to stay and look after her.
JAMIE: Oh, now why can't I go with you?
DOCTOR: Because I particularly want you to give her those pills the moment she wakes up.
JAMIE: Ah, well.
ZOE: Well, why are we going back to the Learning Hall?
DOCTOR: To learn, Zoe. Why else?
SELRIS: I'm coming with you, Doctor.
DOCTOR: Oh, my dear fellow, there's no need for that.
SELRIS: I must know what is happening.
DOCTOR: Oh. Well, certainly. Come along, Zoe.
(The Doctor and Selris leave.)
JAMIE: Zoe, watch him. You know what he's like.
ZOE: Oh don't worry, Jamie. I'll make sure he doesn't do anything rash.

[Learning Hall]

(Selris sends a squad of guards armed with pikes up the steps.)
DOCTOR: Selris, what's that?
(A trap door in the floor at the bottom of the stairs.)
SELRIS: Oh, that leads to the under-hall.
DOCTOR: Oh? What's down there?
SELRIS: Nothing. It's never used.
DOCTOR: I wonder how far underneath? Let's have a look, shall we?
(The Doctor opens the trap door and starts down the steps.)
DOCTOR: Oh, yes, it's a bit dark and musty down here. Zoe, stay up there, will you? We shan't be long.
(Selris follows the Doctor down. Zoe sits herself down at a learning console and puts on the headset. She presses some buttons and a pattern comes up on the monitor in front of her. It resolves itself into series of equations. Her activity alerts the computer. The Doctor and Selris climb back out of the trap door.)
SELRIS: I told you there was nothing down there.
DOCTOR: Ah, but there was, Selris. Something rather curious.
SELRIS: Only the foundations of the machine. It stands on those metal pillars.
DOCTOR: Zoe!
(The Doctor takes the headset off Zoe.)
DOCTOR: Zoe!
ZOE: Oh, you're soon back, Doctor.
DOCTOR: What do you think you're doing?
ZOE: I was just trying the machine.
DOCTOR: You should know better than to do a thing like that.
ZOE: Oh, but Doctor, it was all so easy! The Krotons were very pleased with me.
DOCTOR: Very pleased?
ZOE: Well, I felt they were.
DOCTOR: Zoe! Now, just you listen to me. Whatever else they are, these Krotons are certainly not friendly. Now we know that, don't we?
ZOE: Yes, of course.
DOCTOR: They use these machines to plant impressions on the mind. That's how they've enslaved these people all these years.
SELRIS: Doctor!
DOCTOR: What?
SELRIS: Look at the dial.
DOCTOR: Oh? What of it?
SELRIS: It's amazing! Even the best of our students registered less than half that score.
DOCTOR: Yes, well, Zoe is something of a genius. Of course it can be very irritating at times.

[Selris' house]

(Vana wakes with a start, gasping.)
JAMIE: Vana! You're all right now. You're safe!
VANA: The ball. The burning ball.
JAMIE: What?
VANA: It's over my head!
JAMIE: Vana, there is nothing here now.
VANA: No, no, I saw it. I saw it!
JAMIE: Thara, look.
(Thara takes Vana in his arms.)
THARA: Now Vana, you're all right. There's nothing here. You're safe.
VANA: It was flashing. All the lights. Burning my mind. The lights.
THARA: Vana, you're all right now. You're home.
VANA: Thara, is that you?
THARA: At least she recognises me. Vana, listen. Nothing can hurt you now. You're going to be all right.
VANA: Thara, I went into the machine.
JAMIE: Did you see the Krotons?
VANA: The ball. Flashing! Coming down on me!
THARA: You're quite safe here, Vana!
VANA: No, no.
JAMIE: You'd better take these. Here.
(Jamie gives Vana the tablets and some water.)
JAMIE: Drink up now. All down. That's it.
(Vana falls asleep.)
JAMIE: Flashing ball burning her mind?
THARA: What did she mean? Is it another of the Krotons weapons?
JAMIE: I don't know. Look, you stay here with her. I'll go and get the Doctor.

[Learning Hall]

(The Doctor and Zoe are examining the door.)
ZOE: It's crystalline.
DOCTOR: Yes, it's hard but it's not brittle. I've never seen anything quite like it.
ZOE: What was it like down there?
DOCTOR: Mm? Oh, what Selris calls the foundations. Zoe, it was like a root structure.
ZOE: A root structure? But indicates that
DOCTOR: That this so-called machine is organic in structure. Yes.
ZOE: Well, is that possible?
DOCTOR: Well, why not? Some crystals do resemble simple virus forms. I wish I could get a bit of it for analysis.
ZOE: Well if you're right that means that the whole of this machine is a sort of a living thing.
DOCTOR: Well all life doesn't necessarily have feeling, you know.
(A metallic clang echoes loudly.)
DOCTOR: Great jumping gobstoppers! What's that?
SELRIS: The Kroton's command. It means there is a message for me.
(The hatch where the probe came out is open. Selris reaches in for a message pad.)
DOCTOR: Oh, what does it say?
SELRIS: Class three one nine seven. Selected female, Zo-Gond.
DOCTOR: Zo-Gond? Zoe! They mean you!
SELRIS: They've chosen you as a companion.
DOCTOR: And we all know what happens to them, don't we?
ZOE: Oh Doctor, what shall I do?
DOCTOR: Well, she doesn't have to go, does she? Well, does she or doesn't she?
SELRIS: I'm afraid she must. Complete obedience is the Krotons first command, and if we fail to obey
DOCTOR: They'll destroy you, I see.
ZOE: Oh dear.
DOCTOR: Now do you see what you've done? Fooling around with this stupid machine!
ZOE: Oh, but I'm not a Gond!
DOCTOR: But that machine doesn't know that!
ZOE: Where are you going?
DOCTOR: I'm going to take the test. I can't let you go in there alone! What do I do?
ZOE: Oh, sit down. And put this headset on. And press the button. Press the button!
DOCTOR: All right, there's no need to shout! Now go away and don't fuss me. No, come back. What's this? It's all right, I know. Right, fire away. I'm ready.
(Zoe gestures at him to press the button. The circling symbols come up but he doesn't manage to get them into coherent equations.)
ZOE: Oh. Doctor, you've got it all wrong.
DOCTOR: Oh dear, I've been working in square roots. Can I have that again, please?
ZOE: Well they don't give you a second shots. Well, press the button again.
SELRIS: This is the most advanced machine. Perhaps he can't answer the questions.
ZOE: Of course he can. The Doctor's almost as clever as I am.
SELRIS: I see.
DOCTOR: Oh, now what have I done?
ZOE: Oh Doctor, you've divided instead of multiplying. You must concentrate.
DOCTOR: I am, Zoe! I am!
(The computer watches the results needle flicker wildly from five to ten and try to bounce beyond the upper limit.)
DOCTOR: Yes. I think that's rather better. I think I've scored more than you have, Zoe.
ZOE: You answered more questions. Besides, this isn't supposed to be a competition.
DOCTOR: It's clever, isn't it? The way they make you feel that they're pleased with you.
ZOE: Yes. Perhaps the Krotons aren't as bad as we think.
DOCTOR: What? Of course they are! What happens now?
SELRIS: The Krotons will be waiting for Zoe.
DOCTOR: Well, they can wait. We are going in there together. 
SELRIS: Normally the names don't come through for some time.
ZOE: Well, mine did.
SELRIS: Yes, but perhaps they were impressed with your performance, and that's why.
(The gong sounds.)
DOCTOR: Sounds a bit like a dinner gong, doesn't it Zoe?
SELRIS: Class three one nine eight. Selected male, Doctor-Gond.
DOCTOR: Doctor-Gond. Idiots!
(The doorway opens.)
ZOE: Well, it means you, anyway.
DOCTOR: Yes. Well, are you ready?
ZOE: I suppose we have to?
DOCTOR: Well, we started this, we'd better go through with it. We've got to get to the bottom of this somehow, Zoe.
ZOE: Oh, this is all my fault.
DOCTOR: Oh, cheer up, cheer up. I expect it'll be quite interesting really.
SELRIS: I am sorry, Doctor. My people will always remember you.
DOCTOR: Eh? Oh. Oh, that's very nice of them. Stay close to me, Zoe.
JAMIE: Doctor! No wait, come back!
(The Doctor and Zoe have already stepped through and the door is closing.)
JAMIE: What's happened?
SELRIS: Your people are gone. They are now companions of the Krotons.
JAMIE: What?

[Dynatrope control]

(A door opens and the Doctor and Zoe enter a room.)
ZOE: It is a spaceship.
DOCTOR: Yes, but there doesn't seem to be any crew. Hello? Anybody there? Is anybody at home? Hello?
(They notice two seats.)
ZOE: I think we've been asked to sit down.
DOCTOR: Yes, I think we have, Zoe. Er, Zoe, hold onto the end of this chain.
(The Doctor hands Zoe one end of the chain of his pocket watch.)
ZOE: What for?
DOCTOR: Look up there. It's a force generator. This chain may help to equalise the power load.
ZOE: Well, what are they going to do?
(A hexagonal pillar-like object shines a light on them.)
ZOE: Doctor, I can't move.
DOCTOR: No, it's a forcefield. Try and relax. Relax.
(A device lowers from the ceiling, sending a beam of light whirling around the room.)

[Learning Hall]

JAMIE: But why did you let them go?
SELRIS: It is the command of the Krotons.
JAMIE: Och, the Krotons! They just rap out an order and everyone jumps, don't they? Aye, well, I'm not just standing here to see my
SELRIS: Where are you going?
JAMIE: To find a way into this box of tricks!
(Jamie thumps on the door.)

[Dynatrope control]

(A tube in the pillar is filling with liquid. The Doctor and Zoe are under considerable strain. The chain they are holding begins to smoke. Elsewhere, bubbles form in vats. The Doctor and Zoe pass out briefly.)
DOCTOR: Are you all right, Zoe? Oh!
ZOE: Yes, I think so.
DOCTOR: Oh!
ZOE: What happened?
DOCTOR: Oh, some tremendous power. Oh!
ZOE: They seem to have a way of transferring mental power to pure energy.
DOCTOR: Yes. And they used it, or rather us, to operate a thermal switch.
ZOE: Doctor, look!
DOCTOR: Yes.
(The vats are next to them, bubbling away.)
ZOE: I thought there was a wall here.
DOCTOR: Yes, there was. Zoe, I think that I'm beginning to understand.
ZOE: What's that?
DOCTOR: That's curious. Zoe, I think we've gone and done it.
ZOE: What?
DOCTOR: Well, now just a minute, I've got an idea.
(The Doctor takes out a sample bottle and takes some liquid from the vats.)
DOCTOR: Oh, yes. This is a form of slurry. Crystals in suspension.
ZOE: But what's its purpose?
DOCTOR: Well, life is supposed to have begun on your planet in the sea. Primeval soup, someone once called it. Well, there are lots of sorts of soups, aren't there? I wonder what this sort is?
ZOE: And what do you suppose these are? They look like astronauts' air lines.
DOCTOR: Yes, I think you're right, Zoe. Zoe, look!
(Something solid is forming in the vats.)
ZOE: Oh, Doctor!
DOCTOR: I think it's time we got out of here. Come along!

[Dynatrope corridor]

ZOE: Well, what are we going to do if we do get out? We haven't learned anything yet.
DOCTOR: Yes, we have, once we can analyse this. Now, come on.
(A metal-crystal creature has got out of the vat and has one of the 'air' lines attached to its middle. A second one is in the process of forming.)

[Learning Hall]

SELRIS: There is no way in.
JAMIE: Look, there's a door here if I can just get it open.
SELRIS: No one can enter unless the Krotons wish it.
JAMIE: Well, we'll see about that. All I need is some sort of crowbar.

[Dynatrope control]

(The second creature is out of the vat.)
KROTON: The Gonds should be here.
KROTON 2: They are in the exit shaft.
KROTON: Why? They are conditioned to obey.
KROTON 2: The conditioning may have failed.

[Dynatrope exit shaft]

(The Doctor and Zoe go through an area with tubes on the walls and a strange object in the centre. They push their way past hanging tubes to another door.)
ZOE: It should slide somewhere.
DOCTOR: Yes, there must be a trip-mechanism.
ZOE: Doctor, look. There's a photoelectric cell here. It can't be working.
DOCTOR: Well, if it's not working.
ZOE: Then the Krotons have cut the circuit.
DOCTOR: Yes.
ZOE: Then we're trapped. They know we're here!
DOCTOR: Just a moment, I have an idea.
ZOE: Doctor.
DOCTOR: That piece of mica I picked up. Here we are. Now, if I can use it to bridge the gap.
ZOE: Will mica work?
DOCTOR: Well, the whole machine's made of crystal.
(The Doctor wedges the rock in the hole, and the door opens.)
DOCTOR: Wait! The poison jet.

[Dynatrope control]

(On a viewscreen, the Krotons are watching exit from outside of the Dynatrope.)
KROTON: They have activated the circuit.
KROTON 2: Then the dispersion unit will kill them.

[Dynatrope exit shaft]

ZOE: Doctor, we've got to risk it.
DOCTOR: Yes, but jump down to the side. Don't go down the ramp.

[Dynatrope control]

(The Krotons watch the Doctor and Zoe come out, get off the side of the ramp and run away.)
KROTON: They are not Gonds.
KROTON 2: Why did you inoperate the dispersion unit?
KROTON: We need them alive.
KROTON 2: They have escaped.
KROTON: Keep the scanner on them. We will order the Gonds to capture them and bring them back.
(Jamie is on another monitor.)
KROTON: That is not a Gond.
KROTON 2: It is possible they have evolved.
KROTON: There has not been time. It is a similar biped animal, but not from this planet. It is possible that these higher anthropoids have take over the planet.
(An image of Selris.)
KROTON 2: That is a Gond. These creatures are in alliance with the Gonds.
KROTON: Let us take this one. (Jamie) Its mind will have the capacity we need.

[Learning Hall]

(Jamie is levering at the door with a crowbar when it opens.)
JAMIE: At last.
SELRIS: No! Don't enter.
JAMIE: Look, I have this.
(Jamie and his crowbar enter the Dynatrope.)

[Dynatrope control]

(Jamie enters, and his arm is grabbed by a Kroton's claw. He drops the crowbar and is forced onto a chair.)
KROTON [OC]: Have you damaged it?
KROTON 2: No. It is alive. Animal tissue is weak.
KROTON [OC]: It is recovering. Test its mind.
(Jamie is pinned down by the glowing ball of light.)
KROTON 2: This is not a high-brain. It is a primitive.
KROTON [OC]: Then the power will kill it.
(Jamie collapses.)

Episode Three

[Dynatrope control]

(The Krotons have turned of the mind-draining device early.)
KROTON 2: It is still of value. It can give information about the other creatures.)
(A monitor shows the Doctor and Zoe striding across the wastelands.)

[Wastelands]

ZOE: But this isn't the way to the city.
DOCTOR: No, it's the way to the Tardis.
ZOE: The Tardis? But we can't leave Jamie behind.
DOCTOR: Well, don't worry about him. He's perfectly safe, isn't he? Come on!

[Dynatrope control]

(Jamie awakes.)
JAMIE: Oh, my head.
KROTON 2: Where are you from?
JAMIE: Oh, it's you. I thought I'd dreamt you up.
KROTON 2: Where are you from? 
JAMIE: Earth.
KROTON: You are of the same race as these bipeds?
(The Doctor and Zoe are on the monitor.)
JAMIE: Zoe and the Doctor. Where are they?
KROTON: You are space travellers?
JAMIE: They got out. Good old Doctor.
KROTON: Answer!
(The Kroton grabs Jamie's arm in its pincer.)
JAMIE: You're breaking my arm!
KROTON 2: Do not damage the creature.
(A revolving helmet is lowered to just above Jamie's head.)
KROTON: You and these other creatures are space travellers?
JAMIE: Yes.
KROTON 2: Commander.
(The Tardis is on the monitor.)
KROTON: What is that?
JAMIE: It's the Tardis.
KROTON: What is its function?
JAMIE: It travels through time and space.
KROTON 2: Range zero seven. Dispersion unit on target.
(The Doctor and Zoe enter the Tardis.)
KROTON 2: They are leaving. Shall I fire? 
JAMIE: They're not leaving. They wouldn't.

[Beta's house]

(Beta is adding liquid to a pan hung over a raised fire place in the middle of the room. Eelek and Axus enter with guards.)
BETA: You wish to see me?
EELEK: You got my message?
BETA: That the council requires my advice? On a matter of science, I presume.
EELEK: On a matter of war.
BETA: War?
EELEK: Against the Krotons.
BETA: War against the Krotons? Are you both out of your minds?
(Axus threatens Beta with his axe.)
AXUS: Now you listen to me!
EELEK: Axus! Not yet. Beta, you're a scientist. Surely you want to be free of the Krotons?
BETA: Free, yes. Dead, no.
AXUS: We can defeat them.
BETA: Can we? Our ancestors tried.
EELEK: They were savages. Primitive men with clubs and stones.
AXUS: We are much more advanced now.
BETA: Are we? All our knowledge is given us by the Krotons.
EELEK: Then we can use it against them.
BETA: You're talking nonsense, Eelek. We only know what the Krotons tell us. We don't think. We obey.
AXUS: He could help us if he wasn't afraid of the Krotons.
BETA: Don't you think I want to be free of them? Don't you think I want to discover truth for myself instead of being fed information like a dog with scraps?
EELEK: Then you will help us?
BETA: To fight the Krotons? Listen, I've just been talking to the stranger, the Doctor. He made me realise how pitifully little the Krotons tell us.
EELEK: I would forget the Doctor if I were you, and his friends.
BETA: What do you mean?
EELEK: They submitted themselves to the teaching machines in the Learning Hall.
BETA: What happened?
AXUS: The Doctor and the girl scored the highest result ever. The Krotons summoned them, they went into the machine and the boy followed them.
EELEK: So now they'll be dead like Abu-Gond, or mindless like Vana. So you will help us?
BETA: Give me time, Eelek. There are certain things the Krotons forbid us to study. Fluids which eat away metal and flesh. In time I can develop some way of attacking them.
EELEK: In time! It's always in time, isn't it? Just give us a little more time. Just be a little more patient. Always time, a little more time!
BETA: We've been slaves for a thousand years. Do you think you can free us in one day?
EELEK: Yes!
BETA: Why don't you wait and see what Selris has to say?
EELEK: You will no longer obey Selris. You will obey me.

[Dynatrope control]

(The Tardis is still on a monitor.)
KROTON 2: Shall I fire, Commander?
KROTON: We cannot kill them. We need their minds. You will leave the Dynatrope and fetch them back.
(The junior Kroton picks up a canister from a rack and leaves.)
KROTON: What is the operating principle of your craft?
JAMIE: Er, you mean how does it work? Well, only the Doctor knows that.
KROTON: What is its transference interval?
JAMIE: Transference interval? Well, er, what's that?
KROTON: You have no value.
KROTON 2 [OC]: Vision control required now.
(On the monitor, the Kroton is tottering slowly down the ramp to the wasteland.)
KROTON: On control and proceed.

[Selris' house]

SELRIS: How is Vana?
THARA: Better. Much better, but very tired. She'll be all right by morning though.
SELRIS: That is good news.
THARA: Are the strangers still in the Learning Hall?
SELRIS: They're gone.
THARA: You mean they've left, they've gone back?
SELRIS: They went into the machine.
THARA: What?
SELRIS: The Krotons sent for Zoe, and the Doctor insisted on going as well.
THARA: You let them go? Why didn't you stop them?
SELRIS: What could I do? It is the will of the Krotons.
THARA: But why didn't they run? Why did they go in when they know what must happen?
SELRIS: Because they knew what would happen if they failed to obey.
THARA: But not to them, Father. They could have escaped in their machine.
SELRIS: There is a council meeting.
THARA: Council meeting. Is that all you can ever think about, talking? What about some action, Father? You think the Krotons are still our great benefactors, don't you?
SELRIS: No, Thara. I think of them as enemies. We're powerless against them.
THARA: Well, Eelek is going to do something about it.
VANA: Thara?
THARA: It's all right, Vana. You're quite safe.
VANA: I feel so faint.
THARA: Try to sleep now. We're looking after you.

[Dynatrope control]

KROTON: Radius one eight one vector five. Do not move.
JAMIE: Er, I was just stretching my leg. Look, what are you going to do with me?
KROTON: You have no value.
JAMIE: What do you mean?
KROTON: You will be dispersed.

[Selris' house]

SELRIS: Thara, what did you mean about Eelek?
THARA: I meant you don't know what's happening. He is no longer your deputy. He's taken over as council leader.
SELRIS: He has no authority!
THARA: A vote was taken!
SELRIS: A vote?
THARA: Listen, everybody in the city knows how the Krotons have tricked us. Eelek announced it.
SELRIS: The fool! They will want revenge.
THARA: Well, exactly, and that's what Eelek has promised them.
SELRIS: Can't you understand? Eelek doesn't care what happens to our people.
THARA: Eelek is a patriot.
SELRIS: It is not patriotism to lead people into a war they cannot win.
THARA: We can't let the Krotons rule us forever without putting up some sort of fight.
SELRIS: We will be strong one day. We will fight them.
THARA: After another thousand years?
SELRIS: Eelek must be stopped.
THARA: How? He won't listen to you. Our people want this war because of what happened to Vana and the others.
SELRIS: And how does Eelek intend to fight the Krotons? March on the machine?
THARA: Do you have a better idea?
SELRIS: There is a way we could fight them, and that is by not letting them suspect that they are being attacked.

[Dynatrope control] KROTON: Radius one seven nine, vector five.
JAMIE: Zoe and the Doctor, what are you going to do with them?
KROTON: They are needed for the Dynatrope.
JAMIE: Dynatrope? That's this machine, then?
KROTON: One six eight vector four.
JAMIE: Well, why does it need them? And why have you been killing the Gonds?
KROTON: The Dynatrope needs high brains for transfer power. The Gonds have no high brains.
JAMIE: Aye, and that makes it all right to kill them, does it?
KROTON: That is procedure. Radius one six three vector four.
(Jamie looks towards a canister on the rack.)

[Council chamber]

BETA: Selris should be here. He's still the council leader, or am I mistaken.
AXUS: You are mistaken.
EELEK: Selris is old. In time of war we need a strong leader.
AXUS: And Eelek has taken command.
BETA: So at last you've achieved your ambition, eh?
EELEK: Yes, and I have the support of the whole council.
BETA: It must be quite a change for you to feel popular.
EELEK: And there is a limit to what I will take from you.
BETA: I'm wondering just how popular you'll be when hundreds of our people have been killed. Do you want a repetition of the massacre we suffered when the Krotons first came here?
EELEK: Today we have slings and fireballs. Weapons that will destroy the strongest building to rubble
BETA: Have you ever looked at the wasteland? Nothing grows there even to this day. It smells of death. Compared with their kind of weapons, I tell you we still only have clubs and stones.

[Dynatrope control]

JAMIE: I mean, how would you like to die without knowing the reason, eh?
KROTON: Krotons cannot die.
JAMIE: You mean you can't be killed? You live forever?
(Jamie has got up and is edging towards the rack while the Kroton has its back to him, directing its companion to the Tardis.)
KROTON: We function permanently, unless we exhaust.
JAMIE: Exhaust?
KROTON: Radius one five two, vector three.
JAMIE: How do you mean by exhaust?
KROTON: The exhaust procedure is merely a reversion to basic molecules, but the matter can be re-animated.
JAMIE: Well, what about me, though? I mean, I can't be re-animated. Why kill me?
KROTON: One four nine, vector three.
JAMIE: I mean, what good will it do you?
KROTON: All waste matter must be dispersed. That is procedure.
(Jamie gets his hands on a canister.)

[Outside the Tardis]

(The Kroton surveys the cliff in front of it. Meanwhile, the Doctor comes out of the Tardis with a carpet bag and his sample bottle. Zoe follows.)
DOCTOR: So, these creatures have a life system based on tellurium, eh? It's fascinating, isn't it Zoe? Then that tank must have been a polarised centrifuge.
ZOE: Which we activated.
DOCTOR: Oh, don't blame yourself, Zoe. That machine must have lain around for thousands of years waiting for someone as clever as us to turn up.
ZOE: Just like a giant mousetrap. And those poor Gond students have been the mice.
DOCTOR: Yes, that's horrible. Still, you must admit, that it's a very good way of existing through time.
ZOE: What are you doing?
DOCTOR: Oh, there's some deposits of sulphur around here somewhere.
ZOE: Yes, Jamie remarked about the smell as soon as we stepped out of the Tardis.
DOCTOR: Hydrogen telluride.
ZOE: What? Oh, of course. The worst smell in the world.
DOCTOR: The worst smell in any world.
ZOE: Why didn't I think of that?
DOCTOR: Zoe, I'd say it was a safe bet that that machine is composed of tellurium.
ZOE: Doctor, what do you want sulphur for?
DOCTOR: Oh, it'll come in useful. It's very useful stuff, sulphur, you know. Very useful stuff indeed.
ZOE: I've got a funny feeling we're being watched.

[Dynatrope control]

KROTON: Radius three zero, vector one. Two zero, objective in range.
(Zoe is on the second monitor.)
JAMIE: (sotto) Get back in the Tardis, will you? Go on.
KROTON: Radius one zero.
JAMIE: (sotto) Go on.

[Outside the Tardis]

(The Doctor is filling his bag with rocks.)
DOCTOR: Look at this. It's almost pure sulphur.
ZOE: Oh Doctor, can we go now?
DOCTOR: Yes, in a minute. What do you know about tellurium, Zoe?
ZOE: Well, it's one of the exceptional elements in the periodic table. It's atomic weight is a hundred and twenty eight.
DOCTOR: Yes.
ZOE: And it's atomic number is fifty
(Zoe trails off and looks behind her.)
DOCTOR: Mmm hmm. Well, go on.
ZOE: It doesn't really matter anymore.
DOCTOR: Oh, my giddy aunt.
KROTON 2: You will return to the Dynatrope.
DOCTOR: Oh. Oh, yes. Yes, of course. Well, yes, if you put it that way. I wonder perhaps if I were to
(The Doctor grabs for the bag.)
KROTON: Return!
DOCTOR: Oh, yes. Yes!

[Dynatrope control]

(Jamie hauls the heavy canister off the rack and aims its funnel at the Kroton.)
KROTON: Stop!
JAMIE: Now we'll see if you die or not.
KROTON: Stop! Stop!
(As the Kroton waddles towards him, Jamie manages to get the canister to spew its gas at it.)
KROTON: Stop! Stop!
(The canister stops emitting gas and the Kroton reaches for Jamie.)
KROTON: Stop!
(The Kroton pins Jamie against the wall.)

[Outside the Tardis]

(The Kroton is swinging around as if it is suddenly blind.)
KROTON 2: Direction point. Direction point. I have lost contact.
DOCTOR: Quick, Zoe. Up there. Run!
(The Doctor and Zoe run off.)
KROTON 2: Direction point required immediately.

[Dynatrope control]

KROTON: Radius one zero, vector three.
KROTON 2 [OC]: Do I proceed?
KROTON: No. Wait. The auto-scanner has lost contact. You will destroy the Tardis machine.
KROTON 2 [OC]: Direction point?
KROTON: Radius four one, vector two.
(The image on the monitor stops swinging from side to side and settles on the Tardis.)

[Cliffside]

(Looking down at the Kroton and the Tardis.)
ZOE: Can't it see?
DOCTOR: No, apparently not in the light. It was dark in the machine, wasn't it.
ZOE: Look, it's moving again now.
DOCTOR: Yes.
ZOE: It's going towards the Tardis!
DOCTOR: Yes, it's being directed by the machine's scanners.
(The Kroton fires its canister at the Tardis. When the gas clears, the space is empty.)
ZOE: Oh Doctor, the Tardis!
DOCTOR: Yes.
ZOE: Well, now what shall we do?
DOCTOR: Well, there's nothing we can do till that wretched Kroton moves away.

[Dynatrope control]

(Jamie is on the floor, waking up.)
KROTON 2 [OC]: Further instructions?
KROTON: Return to the Dynatrope.
KROTON 2: Direction point?
KROTON: Reverse the readings.
(The Kroton turns and Jamie pretends to still be unconscious.)

[Cliffside]

(The Kroton leaves, and the Tardis rematerialises further up the cliff.)
ZOE: Look, it's all right again!
DOCTOR: Yes, what a stupid place to land. You can tell that the Captain is not at the helm, can't you?
ZOE: You knew it would vanish like that, didn't you?
DOCTOR: Well it only does that, you see, if I remember to set the HADS.
ZOE: The what?
DOCTOR: The HADS. The Hostile Action Displacement System. If the Tardis is attacked, it automatically dematerialises. Now, I think it's safe for us to move now.
ZOE: Oh, to move where?
DOCTOR: Well, er, we've got to tell the Gonds that we're all right, haven't we? And Jamie'll be worried. Come along, now. Carefully.

[Council chamber]

EELEK: First we destroy the Learning Hall, then we make a frontal attack.
BETA: Suicide!
AXUS: What does the Controller of Science know of war?
BETA: You came here asking my advice. I've given it. Wait until we can develop effective weapons.
EELEK: And how long will that take? I say attack now.
(Selris enters.)
SELRIS: No, Eelek!
BETA: You'll be pleased to know he's taken your place as leader of the council.
SELRIS: To lead an attack on the Krotons?
EELEK: That is my plan.
SELRIS: I forbid it!
EELEK: You can't forbid anything. Order the slings and fireballs to be prepared.
(Gonds leave.)
EELEK: They've heard enough of your plans.
(Eelek leaves.)
BETA: Slings and fireballs will never reach the Krotons while they're still in that machine.
SELRIS: Exactly, Beta, and I have a plan to draw them out. Now under the Hall of Learning there are three pillars which support the machine.

[Dynatrope control]

(The second Kroton has returned, and both are busy at the control panel.)
KROTON: The high brains must be recaptured before exhaust time.
KROTON 2: Captive aliens are dispersed.
KROTON: Check exhaust time.
KROTON 2: Commence check.
(Jamie gets up.)
KROTON: Ileal power stat is?
KROTON 2: Static.
KROTON: Gravitation feed?
KROTON 2: Normal.
(Jamie carefully backs away to the doorway.)
KROTON: Auxiliary output.
KROTON 2: Rising.
KROTON: Dynatrope balance.
KROTON 2: Balance four.
KROTON: The Dynatrope will exhaust in three hours.
(Jamie leaves.)

[Selris' house]

THARA: Are you sure you're strong enough?
VANA: Of course. I'm all right now.
THARA: I can carry you.
VANA: That won't be necessary. I'll walk, Thara.
THARA: It's a long way to the hills.
(The Doctor and Zoe enter.)
VANA: Doctor, you're back!
DOCTOR: Yes, I'm sorry we've been so long.
THARA: But we thought you were dead.
Zoe: Dead?
VANA: Selris said you'd gone into the machine.
DOCTOR: Oh yes, well, we did, but, er, well, what goes in must come out, mustn't it? You're better, aren't you. Sit down.
VANA: Much.
DOCTOR: You mustn't. Oh, I'm glad to see you're going on holiday.
THARA: Holiday? We aren't
DOCTOR: Well it looks as though
THARA: The city's being evacuated.
DOCTOR: Evacuated? What do you mean?
THARA: My father's going to lead an attack against the Krotons. He hopes they'll strike back and come out into the open.
DOCTOR: But didn't he learn his lesson last night?
THARA: He's going to attack the machine from underneath.
VANA: Demolish the machine's supports.
DOCTOR: Oh, I don't think that's a very good idea! Zoe, there's no time to be lost. Will you take us to Beta, please?

[Under Hall]

(The Gonds are using mallets to fasten large chains around the base of the metal supports.)
SELRIS: Ready with the stop-draw? Now!
(The chains are pulled taut from above.)

[Beta's house]

BETA: Thara, if you've come to try to persuade me to leave, you're wasting your time.
THARA: I haven't. The Doctor asked to see your laboratory.
DOCTOR: Can you hold my bag please? There's a small job I want you to do.
BETA: What's that?
DOCTOR: It's sulphur. I've written out some instructions here. I don't know whether you can follow them. Can you?
BETA: Yes, I think so. But the Krotons forbid us to study chemistry.
DOCTOR: Yes. Beta, did it ever occur to you to wonder why?
ZOE: Doctor, where's Jamie? (to Vana) He's supposed to be looking after you. Well, where's he got to?
THARA: He followed you out to the Learning Hall.
DOCTOR: I haven't seen him since this morning.
ZOE: You don't suppose he tried to get into the machine, do you?
DOCTOR: Come on. We must go.
ZOE: Yes, let's!
DOCTOR: Give me a sample of that as soon as you can. (The Doctor and Zoe leave.)
THARA: Vana, I'm staying here to help.
BETA: Oh no you're not. You're going up to the hills, the pair of you.
VANA: Oh don't be ridiculous, Beta. We're not leaving you here. Besides, I feel quite faint. I don't think I could walk a step.

[Dynatrope control]

(The Krotons heads are spinning around.)
KROTON 2: The gravitation feed is dropping.
KROTON: The Dynatrope is moving out of balance. Static beam switch to full volume.
KROTON 2: Full volume on.
KROTON: Systems check commence.

[Under Hall]

(A Gond is cranking a capstan, tightening the chain.)
SELRIS: Shine the light up there.
(The ceiling is cracking.)
BETA: If that comes down we shall all be killed!
SELRIS: But the machine will come down first. Look at the vibration!
(Gonds head for the stairs as the Doctor and Zoe enter.)
DOCTOR: Stop it! Stop it!
SELRIS: Doctor!
DOCTOR: What do you think you're doing, you idiots? Unhook the thing! You're meddling with things you don't understand!
(The Doctor runs to the capstan.)
ZOE: Doctor, look out!
(A piece of the ceiling falls.)
DOCTOR: Zoe! Run! Run!
(Rubble falls on the Doctor, knocking him down and burying him.)

Episode Four

[Learning Hall]

(The roof of the Learning Hall has fallen in too. Thara and Vana enter.)
THARA: I'm going down. You go back.
VANA: Be careful, Thara.

[Under Hall]

ZOE: Doctor!
THARA: Are you all right, Zoe?
ZOE: Yes, I think so.
THARA: Come on, this way.
ZOE: No, we must find the Doctor.
THARA: Well, where is he?
ZOE: Somewhere over there. I saw him fall.
THARA: I'll look for him. You stay under here.

[Learning Hall]

SELRIS: Vana, what are you doing here? Why aren't you in the hills?
VANA: Thara and I stayed behind with Beta to make some acid. We were bringing it here for the Doctor when we felt the earthquake.
SELRIS: The Doctor? Has anyone seen him?
VANA: He's probably buried down there with the digging party.

[Under Hall]

THARA: I've found him, Zoe!
(Thara helps the Doctor up.)
THARA: Are all right, Doctor?
DOCTOR: Yes, yes, I think so. I don't think there's any bones broken. But if they don't get that vibration under control soon
THARA: We must hurry. There's going to be a
DOCTOR: Oh, look out!
(Another piece of ceiling falls, and Thara is trapped by a large piece of masonry on his leg.)
DOCTOR: Thara! Oh, don't worry, we'll get it off you. Zoe! Zoe!
(The Doctor and Zoe struggle to move the rock.)

[Dynatrope control]

(While Jamie picks his way through the shaking spaceship, and through the area of pipes and cable towards the exit, the Krotons heads are spinning very fast indeed.)
KROTON: Cut auxiliaries.
KROTON 2: Auxiliaries cut. Output zero.
KROTON: Feed in emergency power. Gravitation feed check.
KROTON 2: Static.
(Their heads stop spinning.)
KROTON: Dynatrope balance normal.
KROTON 2: The Gonds have attacked the Dynatrope.
(On the monitor, the Doctor and Zoe are dragging Thara to the stairs of the Under Hall.)
KROTON: The two high brains are there. Bring them here.

[Under Hall]

(Vana cradles Thara's head while Zoe checks his leg.)
ZOE: Could be a fracture.
THARA: It feels painful enough.
ZOE: I'll strap it. Oh Doctor, give me the wood.
DOCTOR: Yes, well, hurry up, Zoe. We've got to move out of here, you know.
VANA: You think there'll be another earthquake?
DOCTOR: Oh, that was not an earthquake.
VANA: The noise was coming from the machine, but it's stopped.
DOCTOR: Yes. That means the Krotons are free to deal with us. Haven't you finished yet, Zoe?
ZOE: No I haven't. Hey, can I borrow your braces?
DOCTOR: No! Here, I'd much rather you use this. (pocket handkerchief)
ZOE: Oh, all right.
DOCTOR: Hello.
SELRIS: Yes Doctor, I'm afraid we have failed. The machine is unharmed.
DOCTOR: I'm not so sure - look at that.
(A sphere is leaking fluid.)
SELRIS: What has happened to it?
DOCTOR: I'd say it was no longer functioning under full power. Vana, how is Beta getting on with the acid I asked him to make?
VANA: Oh, he sent this, Doctor.
(Vana gives the Doctor a bottle of liquid.)
DOCTOR: Oh good.
VANA: He only made a small amount to start with.
(The Doctor and Zoe smell the liquid.)
VANA: Is it all right?
ZOE: Poo. Sulphuric acid.
DOCTOR: Yes, basically, with a few things added. Don't touch, it'll burn you.
ZOE: Doctor, what about Jamie?
DOCTOR: Jamie! I'd forgotten all about him in the excitement!
ZOE: Has anybody seen him?
SELRIS: But he followed you.
DOCTOR: Followed us? What, in there?
SELRIS: Yes, I tried to
ZOE: Well, how long ago?
SELRIS: About an hour after you and the Doctor.
ZOE: But Doctor, Jamie wouldn't be any use to them. His mind is completely untrained.
DOCTOR: Yes, and if the machine rejects him like the others? Come on!
VANA: Doctor!

[Dynatrope exit]

(Jamie has made it to the door out to the wastelands but he can't open it. His foot kicks something on the floor.)
JAMIE: The Doctor's piece of mica.
(Jamie picks up the rock and compares it to the hole set into the wall by the door.)

[Learning Hall]

EELEK: Well? Are you satisfied with your efforts?
AXUS: Seven of his working party are unaccounted for. There are four badly injured and I think two are going to die.
SELRIS: They will all be attended to. I am making arrangements.
EELEK: No, you've done enough already.
SELRIS: But you are the one who wanted to fight with the Krotons.
EELEK: I'll fight them. In my own way, in my own time.
SELRIS: I tell you my way is better. Inside the machine the Krotons are invulnerable, but if we can draw them out
AXUS: You've had your chance and look what you've done. The Learning Hall is ruined, our people are dead and wounded, and the machine is untouched.
SELRIS: The machine is damaged!
EELEK: Damaged. It must be destroyed! I will launch a mass attack with slings and fireballs. They are in position now.
SELRIS: And the Krotons will turn our city into another wasteland. Don't be a fool, Eelek.
(Eelek uncovers another corpse.)
EELEK: Do you see what your stupidity has done? You are a traitor. You were dismissed as leader of then council. You had no authority to order this attack!
SELRIS: The leadership of this council is hereditary! My son Thara will replace me!
EELEK: No, I have replaced you! Arrest him!
SELRIS: Wait! Eelek, this is no time for us to be fighting among ourselves. Let me help you organise
EELEK: I have no need of your help.
SELRIS: I said I would bring the Krotons out of the machine.
(The door from the Dynatrope into the Learning Hall opens. A Kroton comes out with a gas canister. Eelek approaches it.)
KROTON 2: Stop!
EELEK: What do you want?
KROTON 2: Where are the high brains?
EELEK: I don't understand.
KROTON 2: The two alien creatures are needed. Where are they?
SELRIS: He means the Doctor and Zoe. What do you want with them?
KROTON 2: Unimportant. Produce them.
EELEK: They're not here.
KROTON 2: Where are they?
EELEK: You say you need them. Why are they so important to you? You never left your machine before.
KROTON 2: Do not argue!
(The Kroton uses the killer gas on a nearby Gond.)
SELRIS: Why did you do that? He was doing you no harm!
KROTON 2: Produce the high brains in fifteen minutes.
EELEK: If we give you the strangers, will you leave us in peace?
KROTON 2: The high brains will enable us to operate the drive mechanism of the Dynatrope.
EELEK: You mean you will go? You will leave our world?
KROTON 2: Yes. But if the two high brains are not brought to the Dynatrope, you will all be dispersed. Do you understand?
EELEK: Very well. If you leave us, you shall have them.
(At the exit door, Jamie presses the mica into the hole, and the door raises just enough for him to crawl under.)
SELRIS: But why, Eelek? It's only a few hours since you wanted to fight the Krotons.
EELEK: If we give them the strangers they will leave us in peace.
SELRIS: But the Doctor and Zoe are our friends. They risked their lives for us.
EELEK: I put the interests of our own people first. Now, keep them all under guard.

[Outside the Dynatrope]

(Jamie has got himself stuck crawling under the door.)
JAMIE: Doctor!
DOCTOR: Jamie!
JAMIE: Quick!
DOCTOR: Jamie, watch out for the poison jets! (Zoe and the Doctor run up the ramp.)
JAMIE: It's just on my back.
DOCTOR: We've got to get you out of here!
(Zoe and the Doctor pull at Jamie's arms.)
JAMIE: I know!
DOCTOR: Jamie!
JAMIE: It's just another inch, I think.
DOCTOR: I think you're getting free.
(They pull Jamie out from under the door.)
ZOE: Quick!
(The three run off to the side just as the nozzles start to release the gas.)
DOCTOR: Oh!
JAMIE: What's been happening? I though that machine was going to shake itself to pieces.
DOCTOR: There's no time to explain, Jamie. How are you feeling?
JAMIE: Well
DOCTOR: Good.
JAMIE: Eh?
DOCTOR: There's something I want you to do for me.
JAMIE: Oh, not again.
DOCTOR: Now Beta is making some special sulphuric acid for us. I want you to go and tell him to make it in bulk.
JAMIE: Yes, but
DOCTOR: As much as he can.
JAMIE: But, Doctor
DOCTOR: There's no time to argue. Now hurry. We'll see you back at the Learning Hall.

[Learning Hall]

EELEK: The strangers are coming back. You two stay here, the rest come with me.
VANA: They're going to walk into a trap.
SELRIS: Yes. Eelek claims to act for the people, but he's only concern is his own skin.
VANA: Oh, if only we could warn the Doctor. He and the girl could get away in their space machine.
SELRIS: I agree. We owe them the chance to escape.

[Beta's house]

(Beta and Jamie are using kerchiefs to protect their lungs from the noxious fumes.)
JAMIE: How long will it be? How long will it be?
BETA: I don't know.
(There is a flash from one of the pots.)
JAMIE: It's not going to explode, is it?
BETA: I don't know.
JAMIE: What?
BETA: I don't know!
JAMIE: Well, I thought you were supposed to be the scientist?
BETA: But I've never worked with acid before.
(Beta puts a drop on his finger.)
BETA: Ow! The Krotons forbid it. Shall we put a bit more in?
JAMIE: Well, why ask me?
BETA: Let's see what happens. We can only blow ourselves up.
(Beta tips more powdered sulphur into his pan as Jamie backs away.)
BETA: Do you think that's enough?
JAMIE: Aye, well, it's enough for me anyway. Quite enough.
(Another pan goes Flash!)

[Learning Hall]

(Thara is still lying on a stone block, helpless.)
VANA: Listen, you distract Axus's attention while I slip away.
THARA: But there are men on the stairs.
VANA: I might be able to dodge by them. Anything's worth trying.
SELRIS: Yes, there is just a chance. But be ready. Axus, a minute.
AXUS: What is it?
SELRIS: In the past you have always accepted my judgement. Believe me, the Krotons are not to be trusted.
AXUS: I don't trust them. But Eelek's right, we're doing the only thing we can.
SELRIS: But if we surrender the Doctor and Zoe, we ourselves will be killed.
AXUS: What do you mean?
SELRIS: I'm sure of it. The Krotons don't care for us. They never have. But while we have the Doctor and Zoe, we have a means of negotiation.
AXUS: And if we don't hand over the strangers they'll kill us anyway. You're getting old, Selris. Your arguments make no sense.
(Axus turns and sees Vana on the steps.)
AXUS: Stop! Stop that girl!
(Vana is halfway up the steps when two guards grab her and bring her down again. She drops the bottle of acid.)
VANA: Help! Let me go! Let me go! Doctor! Doctor!
(Selris picks up the bottle.)

[Dynatrope control]

KROTON 2: Balance zero plus twelve.
KROTON: We have reserve power for twenty seven more minutes.
KROTON 2: Then we shall exhaust.
KROTON: Our function will end.

[Learning Hall]

(The Doctor and Zoe are creeping down the steps. They don't notice Eelek behind them.)
ZOE: What do we do next?
DOCTOR: Well, if only we can get inside that machine again, Zoe.
EELEK: You can, Doctor.
DOCTOR: Oh?
EELEK: We'll help you into it.
DOCTOR: Oh, that's very good of (guards surround them) What? What's all this?
ZOE: Oh. Oh Doctor.

[Dynatrope control]

(The Krotons watch the Doctor and Zoe on the monitor.)
KROTON: The high brains have been captured. Balance check.
KROTON 2: Zero plus nine.
KROTON: Exhaust time twenty two minutes.
KROTON 2: Shall I enter the Dynatrope?
KROTON: Only the two high brains must enter.

[Learning Hall]

EELEK: Well, take them up.
DOCTOR: Really! We will not be bullied. Don't push! (sotto) Vana! Vana, have you got that bottle? It's vital! 
KROTON [OC]: The high brains will enter immediately.
ZOE: I think we'd better do as they say, Doctor.
DOCTOR: Yes. Vana? Oh.
(The guards make sure the Doctor and Zoe go through the door.)

[Dynatrope control]  

KROTON 2: The high brains are entering the Dynatrope.
KROTON: Prepare for take off. Phase one.
KROTON 2: Phase one ready. Shall I destroy the Gonds now? They are of no value.
KROTON: No. The dispersion units use power. We have no power to waste.

[Learning Hall]

VANA: That bottle, Selris.
SELRIS: It's all right. I have it here.
VANA: The Doctor needs it. He says it's vital!
(Selris runs dives through the doorway to the Dynatrope as it is closing.)
VANA: Come back!

[Dynatrope control]

DOCTOR: I believe you wish to speak with us.
(Selris runs in and hands the bottle of acid to the Doctor.)
SELRIS: Doctor!
DOCTOR: Look out!
SELRIS: No!
(The Krotons kill Selris.)
KROTON: Set the intergalactic link.
KROTON 2: Take off, phase two.
KROTON: Prepare to transfer.
KROTON 2: All systems set.
(A console with a flashing globe rises up and the Doctor looks at it.)
KROTON: You will assist us now.
DOCTOR: Assist you? In what way?
KROTON 2: The Dynatrope will exhaust in twelve minutes.
ZOE: Well that's your problem.
DOCTOR: No, no, Zoe. If this machine does run down, there will be the most colossal release of energy. Enough to destroy us, the Krotons and most of the planet. If you want us to help you, you must explain what you want us to do. What is this thing?
KROTON: It transfers the Dynatrope back to our own cosmos. It operates through mental power.
DOCTOR: You've discovered a way of using mental power?
ZOE: And you Krotons haven't enough.
KROTON: Four high brains are needed in relay. There are only two of us.
ZOE: Then how did you get here?
KROTON: No more questions!
DOCTOR: If you want us to cooperate, you must expect questions.
KROTON: Unless you do as we order, you will be dispersed.
DOCTOR: Very well. But that won't help you, will it.
KROTON: We're wasting time. The Dynatrope was part of a battle fleet. Two of our crew were exhausted by enemy fire.
ZOE: You mean they were killed?
KROTON: Ceased to function. We carried out the emergency procedure and landed on the nearest planet. To conserve power we set the Dynatrope in perpetual stability.
DOCTOR: Oh, I see. And you set the machine's systems to educate the Gonds up to the standard you require.
(Behind his back, the Doctor passes the bottle to Zoe.)
KROTON: Yes. They were primitives.
ZOE: Well, you didn't have to kill them to do that.
KROTON: Gond samples were brought in for testing at intervals. The Dynatrope absorbed their mental power into its circuits. The waste matter was rejected.
KROTON 2: And dispersed. Nine minutes to exhaust time, Commander.

[Learning Hall]

(Beta and Jamie carry a large urn down the stairs as guards rush up.)
BETA: Look out!
JAMIE: Hey now, careful. Hey, watch it!
BETA: Watch it.
AXUS: Where do you think you're going? What's that?
BETA: It's something called acid. The Doctor asked me to make it for him.
AXUS: He won't be needing that now. You've been wasting your time.
JAMIE: Where is he then?
AXUS: He's joined the Krotons.
BETA: You mean he's gone into the machine?
JAMIE: Well, what about Zoe?
VANA: Zoe too. The Krotons wanted them, and Eelek surrendered them.
JAMIE: You did what?
EELEK: The Krotons need your friends to enable them to leave our world.
JAMIE: And you just handed them over, did you?
EELEK: If the Krotons will leave our world, they're welcome to your friends.
JAMIE: You miserable
BETA: Careful, Jamie.
EELEK: It's time we were leaving.
JAMIE: Leaving?
EELEK: Unless you want to die.
BETA: What are you talking about, Eelek?
EELEK: Beta, for a scientist, you're very stupid. This Learning Hall and most of our city is built around that Kroton's machine, and once that machine starts moving off
BETA: The whole place will come down.
EELEK: Exactly. And you'll be buried alive.
JAMIE: Aye, well, I'm staying. Somehow I'm going to get the Doctor and Zoe out of there. Beta?
BETA: Yes, I'll stay and help you.
JAMIE: Good.
EELEK: Vana?
VANA: I'll stay and look after Thara. I'm not sensible enough to run away and leave my friends.
EELEK: No. Let them stay, and let them die.
(Eelek and his guards leave.)
BETA: He could be right. you know.
JAMIE: Aye, maybe so. But I'm not going down without a fight. Now where do we put this stuff?

[Dynatrope control]

KROTON: Put on the head sets.
DOCTOR: Now, just a moment. If we're going to help you transfer the Dynatrope back to your own planet, what's going to happen to us?
KROTON: You will suffer no harm.
DOCTOR: Well, how can we be sure of that? We die without oxygen, you see, just as you would die if anyone was to upset the stuff you're drawing from that tank.
KROTON: Take up your positions.
DOCTOR: I was merely trying to explain that if anyone was to contaminate what was in that tank, you'd know what it was like to breathe poisoned air.
KROTON: Six minutes.
(Zoe tips the contents of the bottle into the bubbling tank behind her.)
KROTON: You have no choice. Put on the head set.
DOCTOR: Oh well, I suppose we'd better just take your word for it then.
KROTON: Set the transfer link.
KROTON: Final phase on automatic.
DOCTOR: Oh. Now then, where do you want us to stand?
KROTON: Unimportant.
DOCTOR: Oh. Well, I'll stand over here then.
ZOE: Oh. Oh Doctor, I wanted to stand there.
DOCTOR: Oh, my dear. Oh well, you stand there and I'll stand here. Better still. A much better idea. I'll stand here and you stand over there.
KROTON: Put on the head sets or you will be dispersed!
DOCTOR: All right, all right. How do you wear these things?
(The Doctor puts his on from front to back.)
ZOE: (sotto) Nothing seems to be happening.
DOCTOR: (sotto) Give it time.
(The Doctor makes his head set fall off.)
DOCTOR: Oh! Butterfingers!
ZOE: Oh Doctor, you are clumsy.
KROTON: Enough of this. Put on the head sets.
DOCTOR: Well, it's your fault. You're making me nervous.
(They put on the headsets and then the Krotons start burbling and falling over.)
KROTON: What's happening?
DOCTOR: Down, Zoe!
(Kroton 2 falls on its back and its gas weapon discharges.)
DOCTOR: Are you all right, Zoe?
ZOE: Yes. Doctor, look, it's dissolving.
DOCTOR: Yes. Yes, it's returning to its basic form.
ZOE: Oh, Doctor, these fumes, they're choking.
DOCTOR: Yes, we must get out of here. Look, Zoe. The machine is melting. Come on, let's get out of here before we're trapped.

[Learning Hall]

(Jamie and Beta have found help and are pouring their urns of acid. The Doctor and Zoe run out of the machine.)
JAMIE: Doctor! Zoe!
BETA: What happened?
JAMIE: Did you get on all right?
DOCTOR: Yes.
JAMIE: How are you?
DOCTOR: Yes, well, I'm a little bit shaken, but not half so bad as the Krotons, I can assure you. What're you doing here?
THARA: Look at the machine!
VANA: It's working, Thara! Look, it's working.
ZOE: What made you think of pouring acid on it?
BETA: Well, we reckoned if the Doctor thought it worthwhile experimenting with a few drops, we'd see what a few gallons would do.
DOCTOR: Well done!
ZOE: But how did you know the machine would dissolve?
DOCTOR: Hmm? Well, the machine was eighty percent tellurium, Zoe, and tellurium is soluble in sulphuric acid.
ZOE: But the machine wasn't pure tellurium.
DOCTOR: No, well, the acid wasn't pure sulphuric acid, but it worked didn't it? Come along. Let's get away. I don't like goodbyes.
(The Doctor, Zoe and Jamie sneak up the stairs.)
VANA: It's finished now, isn't it?
THARA: Yes, it is finished. The end of the Krotons. Free at last!
VANA: We still have Eelek to deal with.
THARA: That will be my pleasure. I shall take over from my father as leader of the Gonds, whatever Eelek thinks.
BETA: And we can develop our own science. The Doctor can help. Doctor?
THARA: They've gone.
BETA: But I wanted to ask his advice. There's so much to be done.
THARA: We'll have to find our own answers now, Beta.
(At the base of the cliff in the wastelands, the Tardis dematerialises.)