[Below the Pharos Project antenna]

(The Doctor is lying on the ground after falling from the antenna. He is badly injured.)
NYSSA: Doctor.
TEGAN: Doctor.
ADRIC: Doctor?
DOCTOR: It's the end. But the moment has been prepared for.
(The Doctor points to a ghostly white figure, that walks forward.)
ADRIC: The Watcher.
(The Watcher merges with the Doctor.)
NYSSA: So he was the Doctor all the time.
(Tom Baker turns into the Watcher, then gains the youthful features and short straight hair of Peter Davison. Roll the opening titles.)

[Field]

(Tegan and Adric help the Doctor across the fields while Nyssa runs after them. An alarm is blaring. They nearly get to the Tardis when the Doctor falls into the long grass.)
DOCTOR: I. Oh.
SECURITY: These are secure premises! Now you lot have got some explaining to do.
TEGAN: But the Doctor
SECURITY: He'll be taken care of.
(Two guards grab the young people and haul them away.)
ADRIC: Look, will you let me go!
TEGAN: Look, take your hands off me. This is an official uniform!
NYSSA: Leave me alone!
ADRIC: Now, don't be silly. We would like to help you, but we can't just leave the Doctor. Something might've gone wrong with his regeneration.
(An East Sussex Health Authority ambulance pulls up and the driver gets out.)
SECURITY: Hands up and lean on it. Come on, quick!
(Tegan, Nyssa and Adric are forced to assume the position against the side of the ambulance so the guards can search them. The ambulance men run over to the Doctor with a stretcher and blanket.)
GUARD: There you go.
TEGAN: We're perfectly harmless, unfortunately.
(Tegan sees the keys of the ambulance still in the ignition as the Doctor is carried into the back.)
ADRIC: I thought the whole point of this Pharos Project of yours was to track down alien intelligences. We thought we'd save you the trouble and come to you.
SECURITY: Oh yes?
ADRIC: Yes. We're what you've been looking for. Alien intelligences. You see I come from somewhere up there. That is the way into E-space.
(The ambulance starts up and drives away without the ambulance men.)

[Ambulance]

(Tegan is driving, with Nyssa in the passenger seat.)
NYSSA: Adric, quick!

[Field]

SECURITY: Get him!
(Adric isn't quick enough.)
ADRIC: Get off me!
(Tegan drives to the Tardis while Adric kicks and bites the guards trying to hold him down.)

[Ambulance]

TEGAN: Get the Doctor, quick!

[Field]

SECURITY: I'll hold him. Get the two girls!
(The guards and ambulance men run towards the Tardis. Nyssa and Tegan carry the Doctor inside just in time.)

[Tardis]

NYSSA: This works the door. That's all I know about these controls.
(Behind their backs, the Doctor rushes to the interior door.)
TEGAN: We can't take off without Adric. Doctor! Where's he off to now?
(Tegan goes after the Doctor while Nyssa turns on the scanner to check on Adric. He's still held firmly by the nasty Head of Security.)

[Field]

SECURITY: Right, young man, you better come along with me.
ADRIC: Look, I hope you realise the Doctor's just saved us all from the Master, and now he's going to take off and you'll never have a chance to
(An incongruous stone column materialises nearby. Inside, the Master laughs at the situation.)

[Tardis]

NYSSA: Tegan!
TEGAN: What's the matter?
NYSSA: The Master's Tardis.
(They watch as the column zaps everybody in the field.)

[Field]

TEGAN: Adric! Adric, where are you?
(The column dematerialises, revealing Adric on his knees. The girls run over and help him up, then they go back into the Tardis. They don't notice the column hanging in mid-air nearby.)

[Tardis]

TEGAN: I suppose we'd better take off or something.
(Adric works the controls.)
TEGAN: I hope he knows what he's doing.
NYSSA: He took off once before, he said, but that was by mistake.
(The Tardis dematerialises, followed by the column. The Master is still laughing. Nyssa watches the Earth getting smaller on the scanner.)
NYSSA: Good takeoff.
(Tegan enters.)
TEGAN: The Doctor's very strange.
NYSSA: He's weak. It's the shock.
TEGAN: Well, you'd better go talk to him, because I don't understand this scientific stuff. He's looking for something called a Zero Room.
ADRIC: Zero Room? I'll go.
(Adric leaves.)
TEGAN: That boy never even said thank you.

[Tardis corridor]

(Adric picks up the red coat, then puts it down. Just along the corridor is a thread tied to a door handle. He follows it and finds the Doctor unravelling his scarf.)
DOCTOR: Ah. You've come to help me find the Zero Room. Welcome aboard. I'm the Doctor. Or will be if this regeneration works out.
(The Doctor shakes Adric's hand and walks off. Adric follows.)

[Tardis]

NYSSA: I suppose this is the mean free path tracker. And this panel must be a referential difference.
TEGAN: I know the Tardis is huge, but it can't be taking them this long, surely. What's a Zero Room anyway? The Doctor said something about null interfaces.
NYSSA: I suppose it's some sort of neutral environment. An isolated space cut off from the rest of the universe.
TEGAN: He should've told me that's what he wanted. I could've shown him Brisbane.

[Tardis corridor]

(The Doctor has almost finished unravelling his scarf.)
DOCTOR: Now, ordinary spaces, of course, show up on the architectural configuration indicators, but any good Zero Room is balanced to zero energy with respect to the world outside its four walls. Or however many walls it has.
(The Doctor starts to run his fingers through his hair, and discovers that it is short and straight, not curly.)
DOCTOR: There was a very good polygonal Zero Room under the Junior Senate block on Gallifrey, widely acclaimed for it's healing properties. Romana's always telling me I need a holiday.
ADRIC: But Romana's gone, Doctor.
DOCTOR: Gone? Really? Did she leave a note?
ADRIC: We said goodbye to her at the gateway. Don't you remember?
DOCTOR: Well, if we did, we did.
(He ties the end of the scarf yarn to another door handle.)
DOCTOR: This should get you back to the console room when the time comes.
ADRIC: Are you sure you're alright?
DOCTOR: There are strong dimensioning forces this deep in the Tardis. Tend to make one a bit giddy.
ADRIC: And the regeneration?
DOCTOR: I don't know. I can feel it isn't going to be as smooth as on other occasions. Sooner we get to this Zero Room place, the better, eh?
(The Doctor puts a shoe down as a marker to find his way back, now he's out of wool.)

[Tardis]

NYSSA: These mechanisms are too complex. We just can't fly the Tardis without the Doctor's help.
TEGAN: What if we don't get it? Anything could've happened to him and Adric.
NYSSA: Then the Tardis will just fly on and on, until it crashes into something.
TEGAN: Crash? Is that likely?
NYSSA: Inevitable. The star densities in this galaxy vary inversely with the square
TEGAN: Oh, rabbits!
NYSSA: Tegan, I don't know what's happening to the Doctor, none of us understands it but, I do know that panicking is no use.
TEGAN: You're right. Well, if only we had a manual.
NYSSA: There's nothing we can do here. I'm going to try and find them.
TEGAN: Wait! You don't know those corridors. I got lost in them when I first came into the Tardis and I can tell you they're a nightmare.
NYSSA: Then you'd better stay here.
TEGAN: I'll come with you.
(Tegan takes her shoulder bag off the console.)
TEGAN: Wait a minute!
(She reads a message on a screen.)
TEGAN: Tardis Information System. Ready For Entry.
NYSSA: A databank!

[Tardis corridor]

(The Doctor is now tearing up his waistcoat to leave markers at junctions.)
DOCTOR: I left a waistcoat like that on. Ever been to Alzarius?
ADRIC: I was born there, Doctor.
DOCTOR: Really? It's a small universe, isn't it.
(The Doctor starts behaving like William Hartnell.)
DOCTOR: I wonder, boy, what would you do if you were me, hmmm? Or perhaps I should ask, what would I do if I were me.

[Tardis]

TEGAN: Will it tell us how to fly the Tardis?
NYSSA: I'm sure that's in here somewhere, once we find the index file.
TEGAN: How do we find the index file? Of course, if we had an index file, we could look it up in the index file, under index file. What am I saying? I'm talking nonsense.
NYSSA: Recursion isn't nonsense.
TEGAN: Eh?
NYSSA: That's an example of recursion, when procedures fold back on themselves. If you had an index file, you could look it up in the index file.
TEGAN: If. My Dad used to say that if was the most powerful word in the English language.
NYSSA: Recursion's a powerful mathematical concept, but I don't see how it can help us now.
TEGAN: If. I F! Stands for index file!

[Tardis corridor]

(The Doctor is now in Patrick Troughton mode.)
DOCTOR: Not far now, Brigadier, if the Ice Warriors don't get there first. Oh no. Oh dear. We've wandered into the wrong corridor. We must be close to the main Tardis drive now. Jamie. Jamie, you go back.
ADRIC: No. I have to stay with you, Doctor.
DOCTOR: No, nonsense, be sensible, go back! When I say run, run! Don't you understand? The regeneration is failing.

[Tardis]

TEGAN: I F! It works. Let me have a go on it.
NYSSA: Look up destination setting.
TEGAN: Right. D S. You know, once you get into it, this whole funny system on the Tardis does start to make a sort of weird sense. Except this. (reads) Tardis Flight Data. Programmed Journey. Departure Earth, Pharos Project. Destination Hydrogen In Rush, Event One.

[Tardis corridor]

(The Doctor is sitting on the floor as Adric walks off.)
DOCTOR: Adric! Adric, not that way! Adric. I remembered his name.
(Meanwhile, near the console room, Tegan has found the start of the yarn.)
TEGAN: Seems the old doc is coming unraveled in more ways than one. Look, you'd better go back to the console room.
NYSSA: We're on a programmed flight. We won't crash. At least I don't think so.

[Outside the Changing room]

DOCTOR: Adric!
(A full cheval mirror with descant recorder on the top, and a hat stand with panama, green Wellington boots and light beige coat with red trim on a hangar. The Doctor gazes at his new features.)
DOCTOR: That's the trouble with regeneration. You never quite know what you're going to get.
(He tries playing the recorder, but blows too hard. It squeaks.)
DOCTOR: No.
(Then he finds a cricket bat by the hat stand.)
DOCTOR: Ah! Dear me. Needs a drop of linseed oil though.
(The Doctor turns and spots a white door nearby. He opens it to reveal a changing room, complete with cricket bats in a rack, shields on the wall, a notice board and some whites scattered on a bench and hamper. The Doctor goes inside and closes the door.)

[Tardis corridor]

(Adric is wandering around when Nyssa finds part of the waistcoat.)
TEGAN: No, that looks like the end of the trail.
(Nyssa opens a nearby door to reveal a packing case labelled Handle with Care and some dust sheets.)
NYSSA: This part of the Tardis can't have been used for centuries.
TEGAN: It does go on and on.
NYSSA: Deeper and deeper.
TEGAN: Yes, I get that feeling too, that we're going downwards.

[Master's Tardis]

(The Master is following Adric on his scanner.)
MASTER [OC: Oh, no, you can't escape. You're mine, Adric. Mine! Until we have completed our final task.

[Outside the Changing room]

(The Doctor emerges, having put on a cricket jumper over his shirt and changed into beige striped trousers and plimsolls. He tries a few batting shots in front of the mirror, then puts on the coat and panama. He takes the hat off again.)
DOCTOR: Well, I suppose I'll get used to it in time.
(There is the sound of footsteps, then a door closing with an echoing thud.)
DOCTOR: That's it. That's the door!

[Tardis corridor]

(Tegan and Nyssa hear the sound too.)
NYSSA: This way, come on!
(Tegan leaves her bag by the wall. They run straight into the Doctor.) 
NYSSA: Doctor!
TEGAN: Thank heavens.
DOCTOR: The Zero Room door, I heard it slam.
TEGAN: Doctor, are you all right?
DOCTOR: Fit as a fiddle, Vicki, but something very peculiar is going on in the Tardis. The Zero Room. Have you seen it anywhere?
TEGAN: I think the noise came from this direction.
DOCTOR: Good. I'll follow you.
(And runs off ahead of them.)

[Corridor junction]

(Three pillars and the middle one has a nice horseshoe shaped railing round it.)
TEGAN: Must be around here somewhere.
(The Doctor touches a red line drawn on the wall.)
TEGAN: Doctor?
DOCTOR: Hello, carmine seepage.
TEGAN: Actually, Doctor, it's me. My lipstick. We passed this way before.
DOCTOR: Oh that's a relief, I thought the Tardis auto-systems were playing up again. Dreadful. Always going wrong. It's time we went to Logopolis to get it all sorted out once and for all.
TEGAN: We've been already, Doctor.
NYSSA: Doctor? What does the Zero Room look like?
DOCTOR: Zero Room? Oh, it's very big, empty, sort of grey. Pinkish-grey.

[Zero room]

(Nyssa is standing in such a room behind the horseshoe railing.)
TEGAN: Come on, Doctor. Through this way.
(Once inside, the Doctor relaxes.)
DOCTOR: Thank you. You must be Tegan. Works even better if you close the doors, Nyssa.
TEGAN: It smells like roses.
DOCTOR: Yes. I've never quite understood why. It's quite peaceful, isn't it.
TEGAN: Peaceful. Doctor it's like
NYSSA: Like Traken used to be.
TEGAN: Will you have to stay here long?
DOCTOR: Oh, just until my dendrites heal. (taps his head) The nervous system's a very delicate network of logic junctions.
NYSSA: The synapses, yes.
DOCTOR: Oh, yes, I was forgetting, Nyssa, bioelectronics is your strong point. Yes, well, my tussle with the Master came at precisely the wrong moment. When the synapses are weak they're like radio receivers, picking up all sorts of jumbled signals.
TEGAN: I get it. The Zero Room cuts out all interference.
DOCTOR: Completely! Even the gravity's only local. Goodness me, I'm tired.
NYSSA: But there isn't even a bed.
DOCTOR: Bed? Oh, I don't need a bed. Not in the Zero Room.
(The Doctor puts his fingers to his temples, then begins to rotate in the air until he is lying down.)
DOCTOR: One of the advantages of stark simplicity.
TEGAN: Can anybody do that?
DOCTOR: Oh, you don't do it. It just sort of comes to you, like sleep. Very like sleep. We only just made it to the Zero Room in time. 
DOCTOR [OC]: This regeneration is going to be difficult, and I shall need you all, every one of you. You, Tegan, you have it in you to be a fine coordinator, keeping us all together during the healing time. Nyssa, of course, has the technical skill and understanding. All the information you need is in the Tardis databank. I'm sure you can find your way to it.
TEGAN: We already have, Doctor.
DOCTOR [OC]: Good, good. Of course you have. And Adric, Adric with his badge for mathematical excellence. Adric is the navigator. He knows the way. He knows me, my old self. Adric, you must help me heal the disconnection. Your role is very crucial.
TEGAN: Adric.
NYSSA: Oh! Adric!
(One of the giant roundels on the wall shows Adric caught in a web of wires.)
TEGAN: Adric. What are you doing up there?
ADRIC: A trap. He set a trap. The Master!
NYSSA: The Master? Where?
ADRIC: Me! I'm the trap. I locked the coordinates. Event One!
TEGAN: Adric, hold on. I'm coming up to get you.
ADRIC: No, no, this isn't me. It isn't me. It's an illusion. Projection! Block transfer. Tegan, the coordinates.
(The image of Adric dissolves.)
TEGAN: Horrible.

[Master's Tardis]

(This is where Adric is really held prisoner in the web.)
ADRIC: Escape. Must escape.
MASTER: So, these simulated projections are real enough to have a will of their own. Almost.
ADRIC: Can't, can't reach me in the Zero Room.
MASTER: Is that what you thought? Well, my dear young man, it's your own computational powers that made the block transfer possible. If escape were that easy, Adric, we could all be free of this nasty world. Now, we must save your energies. There's so much yet to be done.
(The Master uses a control device, and Adric passes out.)

[Zero room]

(The Doctor is still sleeping on his bed of air.)
NYSSA: We can't tell him now. He's in a dangerously unstable state.
TEGAN: Adric was trying to warn us.
NYSSA: The coordinates, and something about a trap. You stay here and keep an eye on the Doctor.

[Outside the Zero room]

TEGAN: Where are you going?
NYSSA: Console room. Look after the Doctor.
(Nyssa sees Tegan's lipstick on the railing. It appears to have melted. The lines they drew on the walls with it have started to run, too. Then there is a knocking sound.)
NYSSA: That's odd.

[Zero room]

TEGAN: Poor Adric. If only we could do something.
(The Doctor has drifted down to the floor.)
DOCTOR: What's the matter?
TEGAN: Sorry, I didn't mean to wake you.
DOCTOR: There seems to be something distinctly wrong. I can feel it.
(The Tardis walls are getting hot, and the Cloister Bell is tolling.)
DOCTOR: Shush. The Tardis Cloister Bell. Imminent disaster.
TEGAN: For us?
DOCTOR: Oh, worse than that. The Tardis is in danger. Who's in the console room?
TEGAN: Nyssa.
DOCTOR: And Adric.
TEGAN: Adric's
DOCTOR: Well, is he, or isn't he?
TEGAN: Well, Doctor

[Outside the Zero room]

TEGAN [OC]: No, you can't go out there.
(The Doctor walks out and collapses. Tegan rushes to help him back inside the room.)
DOCTOR: Adric isn't what? Tell me!
TEGAN: It doesn't matter.

[Zero room]

TEGAN: Look, you stay here. I'll go. After all, I am the coordinator.

[Tardis]

(Nyssa reads the data screen, which is red and flashing. Tardis approaching Hydrogen In-Rush, Event One. Environment beyond engineering tolerances.
Meanwhile, Tegan finds the end of the scarf yarn.)
NYSSA: (reads) Hydrogen. Abundant element. Highly explosive in the presence of oxygen. Believed to be the basic constituent out of which the galaxy was first
(Realisation dawns as Tegan runs in without her jacket.)
TEGAN: Oh, this heat. Has something gone wrong with the Tardis air-conditioning?
NYSSA: Of course, that's it. It's not the Tardis.
TEGAN: Well, what else could it be?
NYSSA: Outside! You'd better read this.

[Outside the Zero room]

(The place is filling with steam or smoke.)
DOCTOR: I've got to do something.

[Tardis]

TEGAN: Event One.
NYSSA: A trap, Adric said. This is a time machine.
TEGAN: And we're travelling backwards in time. Back to first event!
NYSSA: The creation of the galaxy out of a huge in-rush of hydrogen. We're heading straight into the biggest explosion in history!
(The Tardis is shaken hard. Everyone looses their footing. The Doctor is knocked out and Tegan burns her hand on the console. The scanner activates to show a happy Master.)

[Master's Tardis]

MASTER: Farewell, my friends. Farewell forever!

Part Two

[Tardis]

NYSSA: That face. I hate it!
TEGAN: We must do something.
NYSSA: There's only one thing we can do.
(Nyssa turns off the scanner.)
TEGAN: And?
NYSSA: That's all.
TEGAN: All? Hogwash. We found the databank. Maybe we'll learn how to fly the machine.
(Another explosion knocks them sideways.)

[Outside the Zero room]

(It also knocks open a roundel containing medical supplies. The Doctor gets up and feels the back of his head, which is bleeding, then the supplies eject themselves onto him. He reads the labels.)
DOCTOR: Tablets. The mixture. The ointment.

[Master's Tardis]

(The Tardis is on his scanner, and the Master cannot stop laughing.)
ADRIC: No!
MASTER: You must control these dangerous emotions, Adric. They'll only cause you pain, besides interfering with the reception. Now, closer!

[Outside the Zero room]

DOCTOR: The potion. The solution. Oh, my little friend, if only you were.
(He puts some of the solution onto a pad and puts it onto the back of his head. He winces. The Tardis is shaken by another explosion. He looks up to see an electric wheelchair rolling towards him. The Tardis loves her Doctor.)
DOCTOR: Oh, transport of delight.

[Master's Tardis]

MASTER: You have something to say? Well?
ADRIC: I'll fight you. I won't let you harm the Doctor, I won't!
MASTER: Closer, Adric. I must see them.
(The Tardis becomes visible through the scanner interference.)

[Tardis corridor]

(The Doctor spots a piece of the waistcoat on the floor. He circles to pick it up, then quotes Fortinbras from Hamlet.)
DOCTOR: Go softly on!

[Tardis]

NYSSA: You don't understand the physics of the situation. We're already caught in the field of Event One. It's pulling us in faster and faster.
TEGAN: A sort of gravity.
NYSSA: The time force. It's many orders of magnitude greater.
TEGAN: But people escape from gravity all the time. What we need is some kind of rocket thrust. All right, enormous thrust. But there must be some way the Tardis can do that.
NYSSA: But nothing's happening. The temperature's defeating the automatic controls.
(The Doctor enters on his wheelchair.)
TEGAN: Doctor!
NYSSA: You must go back.
DOCTOR: Smoke! Heat! And noise! Adrenaline! And neuropeptides! The brain's working!
TEGAN: Neuropeptides? What's he talking about?
NYSSA: The excitement's changing his biochemistry. It's only temporary but perhaps he can help us.
TEGAN: We must take him back. It's not safe.
NYSSA: But the Doctor's our only chance, unless we can find some way of getting the temperature down.
DOCTOR: The manual override, Nyssa. I'll have to explain how to vent the thermo-buffer. Listen very carefully. My concentration may go again at any moment.
(The Doctor puts on a pair of half-moon reading glasses and starts writing in a notebook.)

[Master's Tardis]

(The Master watches all this on his scanner.)
ADRIC: Doctor.
MASTER: I sympathise. This is all too easy. A great pity. These facile victories only leave me hungry for more conquest.

[Tardis]

(Nyssa removes a roundel to reveal a lever pointing to the right. She turns it anticlockwise until it points downwards.)
DOCTOR: This will be simpler, of course, if you go into hover mode first, always remembering of course not to reverse the polarity of the neutron flow. The whole system is on manual now. This is where it starts to get really dangerous.
TEGAN: Not till now?
DOCTOR: The temperature will start coming down fairly quickly, but without that stimulus my neuropeptide level will fall to normal.
TEGAN: Don't worry, Doctor. We'll get you straight back to the Zero Room.
DOCTOR: Good, good. Now, as soon as full console functions are restored, you can start to reprogram the architectural configuration. I'd better show you.
(The Doctor gets out of his wheelchair and burns his hands on the Tardis console.)
DOCTOR: Er.
(Nyssa watches the colour in the wall change from red to yellow to green and finally blue. She replaces the roundel.)
TEGAN: But how will it help to change the Tardis rooms around?
DOCTOR: Oh, the architectural configuration system can do more than that. We can actually delete rooms.
TEGAN: Delete them? You mean zap?
DOCTOR: Yes, exactly. Zap! Enough zap and you have your thrust. Now, follow this very carefully.
TEGAN: You bet your life.
(Tegan takes notes of what he is doing on the console.)

[Master's Tardis]

MASTER: Perhaps this little demonstration will give you some glimpse of my real power.
ADRIC: Power you're getting from me! From my computations!
(The Master pushes a button on his hand-held controller and rises up to Adric's level.)
MASTER: In part, certainly. Even as an enemy, you're useful. But how much more useful as an ally.

[Tardis]

DOCTOR: Now, have you got that?
TEGAN: Yes. We're converting the mass of the deleted Tardis rooms into momentum. But I still don't understand about momentum.
DOCTOR: Mass in motion. Thrust, if you like. Time for lessons later.
TEGAN: Does it mean burning up part of the Tardis?
DOCTOR: Yes, well, don't worry, it works. We had to do that once with Adric to get away from. By the way, where is Adric?
TEGAN: Adric? He's er
DOCTOR: Well, where? We need him!
NYSSA: It's cooler already. That's something.
DOCTOR: Well?
NYSSA: Adric's not here, Doctor. You see
TEGAN: We thought he was in the Zero Room.
DOCTOR: Well, tell me later. There's not much time. Once the star field reaches critical mass, we'll be shut into the in-rush. Where were we, Jo? Deleting rooms.
(The Doctor sits in the wheelchair, in some pain.)
NYSSA: But Adric.
TEGAN: Are you okay, Doctor?
NYSSA: His adrenaline's normalising. It was helping to bridge the synapses.
DOCTOR: Shush. Come on, we've got to finish this. Seventeen thousand tons of thrust. Say twenty five percent of the architecture.
TEGAN: A whole quarter of the Tardis?
NYSSA: Which twenty five percent, Doctor?
DOCTOR: Doesn't matter, same thrust.
NYSSA: No, it isn't. We don't want to jettison the console room.
TEGAN: That's a thought. Doctor, please. One last thing.
DOCTOR: Yes?
NYSSA: How do we make sure we don't jettison the console room?
DOCTOR: Oh, yes. That's the trouble with manual override.
NYSSA: What's the problem?
DOCTOR: Get K9 to explain it to you. Good luck.
(The Doctor closes his eyes and starts to relax.)
TEGAN: Thanks, Doc. I think we might need it.

[Master's Tardis]

MASTER: Well, Adric, this is my proposition. Life will immediately become more comfortable for you if you join forces with me. Or do you prefer to remain in the web throughout eternity. A mere utility. You may speak.
ADRIC: What do you want me to do?

[Tardis]

TEGAN: It seems so still now.
NYSSA: We've passed the boundary layer. We're heading straight towards the in-rush. Thirty eight seconds.
TEGAN: How can you be so calm? We're playing Russian roulette with the Tardis.
NYSSA: Thirty one seconds.
TEGAN: If I press that button it could be the console room we jettison!
NYSSA: If. You taught me something. As a scientist it's easy to be tyrannised by facts.
TEGAN: If can work. But I didn't know it'd be this chancy.
NYSSA: Because it is still an if. You have to turn the if into a fact. Five seconds, four, three, two, one.
(Tegan presses the button. KaBOOM in a big flash of light.)

[Master's Tardis]

MASTER: So, this petty feud with the Doctor is over, Adric. You were wise to join me.
ADRIC: You've got to keep your side of the bargain.
MASTER: But are you truly sincere? I sense a barrier behind your eyes. Are you keeping something from me?
ADRIC: How could I?
MASTER: The universe is purged of the Doctor and his impossible dreams of goodness. You and I belong to the future.
ADRIC: The Doctor was doomed. I see that now.
MASTER: He might've escaped from the in-rush. Yes, even that was a possibility. But I had installed a trap behind that trap that would have been a joy to spring.
ADRIC: Yet another trap?
MASTER: A journey back in time. Long awaited. Why are you so curious?
(Adric jerks with pain. The Master's scanner is full of interference.)
MASTER: Residual voltage? You're receiving an image! What are you concealing from me? Some distant event beyond the range of my own scanner? I'll burn through your barrier, boy. Bring it to me!
ADRIC: No. No!
(The Tardis reappears on the scanner.)
MASTER: It can't possibly be.

[Tardis]

TEGAN: All Time Lords regenerate according to this databank. You'd think there'd be something in here about what to do when it goes wrong.
NYSSA: We must get him straight back to the Zero Room.
TEGAN: Wait a minute. (reads) Ambient complexity is the cause of many of these failures of regeneration. Some real locations are known to have properties similar to Zero environments and, in some cases, are eminently more effective.
NYSSA: That's it. We need to take him somewhere uncomplicated. Somewhere away from technology.
TEGAN: (reads) Classic Plainness as exemplified by regions like Dwellings of Simplicity.
NYSSA: Dwellings of Simplicity. Castrovalva. Where's that?

[Master's Tardis]

MASTER: Closer, boy. I must see him, hear him.
ADRIC: No. No!
MASTER: So, Doctor, you have survived. But at what cost, I wonder.

[Outside the Zero room]

(Nyssa is pushing the Doctor along in the wheelchair.)
DOCTOR: Castrovalva.
NYSSA: The data bank is certain it's the best place to recuperate. It's in Andromeda. A small planet of the Phylox series.
DOCTOR: How do we get there?
NYSSA: Don't worry, Doctor. Tegan thinks she's learnt how to set the coordinates.
DOCTOR: Are you sure?
NYSSA: Well, that's what she said.
DOCTOR: When the Tardis is on manual, you can't be certain of anything.
NYSSA: What do you mean?
DOCTOR: It's harder to fly than you think. I mean, you don't just flick a switch.

[Tardis]

TEGAN: Castrovalva, here we come.
(She puts her hands together in prayer.)
TEGAN: Please?
(Tegan flicks a switch and the Tardis tilts to the right.)

[Outside the Zero room]

DOCTOR: So, this air hostess person's flying it, eh? Well I wish her the best of luck.
NYSSA: Seems you were wrong about Tegan's ability to fly the Tardis, Doctor.
DOCTOR: I don't think so.
NYSSA: Then who's controlling the ship?
DOCTOR: What? I don't know.
NYSSA: It must be Tegan.
DOCTOR: Can't be.
NYSSA: Don't you worry about it, Doctor.

[Tardis]

TEGAN: Well, we are moving.

[Outside the Zero room]

NYSSA: We'll soon have you safe. Here's the Zero Room.
(Nyssa opens the doors to reveal a wall.)
DOCTOR: Jettisoned.

[Tardis]

(Tegan reads Standard Flight Procedures, stage 387. She's put her jacket back on.)
TEGAN: On zeroing the coordinate differential, automatic systems reactivate the real-world interface. See Main Door, The Opening Of. Not much here about landing procedure. Hope it's as simple as it seems.

[Outside the Zero room]

DOCTOR: Handy little device, the sonic screwdriver. Got me out of a lot of scrapes.
(Nyssa takes the screwdriver from his trembling hands.)
NYSSA: What do I do with this?
DOCTOR: Unscrew the hinges! If you wouldn't mind.

[Tardis]

(A planet looms large on the scanner.)
TEGAN: Castrovalva. Landing procedures. Here's hoping.

[Outside the Zero room]

NYSSA: Unscrewing the doors won't get us into the Zero Room, Doctor. It's gone. We burnt it up. Doctor, please. What do I do next?

[Tardis]

TEGAN: Hmm. Well, we can't hang about here all day.

[Outside the Zero room]

(The Doctor is unconscious.)
NYSSA: There's no way into the Zero Room, Doctor. It's gone. What do we do?
(The Tardis lurches to the left and the unhinged door falls forward, hitting the railing and thus missing the Doctor's head.)

[Tardis]

(The Tardis has landed at an angle of about forty degrees from vertical.)
TEGAN: Touchdown! We've made it. We've made it!

[Outside the Zero room]

DOCTOR: Well done, Nyssa. That's the idea. We make another Zero Room out of what's left.

[Woodland]

(The Tardis is lying on a slope in a lush woodland clearing with lots of cow parsley and bracken. Tegan looks out of the door. Welcome to Buckhurst Park, Withyam.)
TEGAN: Not up to CAA standard, but a landing's a landing! Castrovalva can't be far.
(Nyssa pushes the Zero room door along on the wheelchair. It appears to be extremely heavy.
Tegan climbs a tree to get her bearings. She smiles.)

[Tardis]

(Nyssa is dismantling a roundel from the door. She places it in a hole in a man-sized box on the floor.)
NYSSA: It looks very small, Doctor.
(The Doctor is inside the box. We can only see his head.)
DOCTOR: And unlike the Tardis, it is very small.
(Tegan half-falls in.)
TEGAN: Well, it's not far to go, anyway.
NYSSA: You've seen it?
TEGAN: It's an afternoon's walk away, more or less.
NYSSA: We'll be carrying the Doctor, don't forget.
DOCTOR: Oh, just the Zero Cabinet.
TEGAN: Eh?
DOCTOR: You won't feel my weight. I'll make it easy for you. I'll be levitating.

[Woodland]

(The Zero Cabinet and the wheelchair are outside, up the slope from the Tardis. Nyssa has found a pair of trousers to match her jacket, instead of the tulle skirt.)
TEGAN: That's much better.
NYSSA: There's a whole room full of clothes if you want to change.
TEGAN: No, we should make a start. It's that way.
NYSSA: I still say we should get help from Castrovalva.
TEGAN: Why? He's no problem while he's levitating. We can roll him along in the chair.
(But the cabinet is too heavy to lift off the ground.)
NYSSA: Doctor? Doctor?
(The front slides down to show the Doctor's head.)
NYSSA: What happened?
DOCTOR: So sorry. Lost concentration for a moment. Very tired.
NYSSA: I really think we should get help.
DOCTOR: Please, there's not much time. Thank you.
(The cabinet closes up. Nyssa puts the wheelchair on a path and this time they easily lift the cabinet and balance it across the arms.)
TEGAN: Well done, Doctor.
(They start to wheel the Zero Cabinet through the woods. They head up a slope by a stream until they get to a header lake.)
NYSSA: Maybe it's that way.
TEGAN: I did see it and I'm sure it's that way.
NYSSA: I think he's got heavier.
TEGAN: I hope you're wrong. Come on, Doctor. Help us to help you.
(They lift the Cabinet off the wheelchair, which promptly escapes to fall into the stream. There's a brief flame as the electrics short out. Nyssa scrambles down to try and retrieve it, but slips and falls into the water, losing her mantilla in the process.)
NYSSA: Urgh.
(Later, the wheelchair has been recovered.)
TEGAN: Are you sure I can't give you a hand?
NYSSA: This is going to take a bit of molecular adjustment.
(But her gizmo is full of stream water. Someone is watching them.)
TEGAN: Oh, no. What are we going to do now?
(Nyssa and Tegan carry the cabinet away, leaving behind the wheelchair and Nyssa's waistcoat.)
NYSSA: Are you sure this is the right way?
TEGAN: It'd better be! You know, this thing is still getting heavier.
(Further on, they've swapped ends.)
TEGAN: The old Doc's levitation's wearing a bit thin.
NYSSA: He's lost his concentration again.
(They put the Cabinet down.)
NYSSA: If we don't find Castrovalva soon. Doctor?
TEGAN: Shall we take a peek at him?
NYSSA: Nobody can open this cabinet unless the Doctor wants it open. The internal interfaces are fused by strong force interaction and
TEGAN: Look! Castrovalva.
(A pink granite castle sits on top of a very steep set of cliffs. The girls conceal the Cabinet in the bracken. Nyssa adds more fronds.)
TEGAN: Never mind that. We've got to get help. 
NYSSA: Just in case.
TEGAN: It'll be night before we know it.
(Someone with a large orange plume on his helmet, and a nasty looking Assegai type spear is watching them from the bracken.)

[Base of the cliffs]

NYSSA: Still no way in.
(They walk on round Harrison's Rocks, Groombridge. The warrior has been joined by a second with a collection of coloured feathers in his helmet.)
RUTHER: And here is where you saw them? Mergrave must be told this.
(Meanwhile, the Doctor has woken, and opens his Cabinet.)

[Partway up the cliffs]

TEGAN: Castrovalva's harder to get into than the Doctor's cabinet.
NYSSA: Well, perhaps we should get back there. We might be able to wake him.
TEGAN: How? We can't get into him.
NYSSA: Well, we'll have to think of something. It does seem the only way.

[Woodland]

(The cabinet is no longer hidden by bracken.)
NYSSA: Doctor?
(There is fresh blood on the grass.)
TEGAN: Blood.
NYSSA: He's gone. The Doctor's gone!

Part Three

[Woodland]

NYSSA: The cabinet was secure.
TEGAN: So he had to have opened it himself.
NYSSA: It must have worked. The Zero effect. He was feeling better.
TEGAN: Until whatever happened, happened. We've got to find him.
NYSSA: There's more blood here. And there, and there.
(They follow the trail until they get to a view of the cliffs again.)
TEGAN: Castrovalva.
(A group of plumed warriors rise up from the bracken around them.)
TEGAN: Run!
(Tegan and Nyssa hide in bracken. No one is following them.)
NYSSA: We've got to find the Doctor. Until he's properly regenerated he's terribly vulnerable.

[Base of the cliffs]

(The Doctor is lying with his ear to the hard-packed ground. The blood trail continues past him to the rocks.)
DOCTOR: Hmm. Twelve of them at least. War party, maybe.
(Tegan and Nyssa approach from the woodland to see the Doctor beginning to make his way up the cliffs.)
NYSSA: There he is.
TEGAN: Perhaps he's found a way in.

[Cliffs]

NYSSA [OC]: Doctor!
(The Doctor holds onto a sapling growing from the side of a boulder and looks down. Not a wise move. He grabs the rock.)
NYSSA [OC]: Doctor!
DOCTOR: Doctor? Everyone's looking for him.

[Entrance]

(The warriors carry a dead animal into a cave entrance in the cliffs. A man with the biggest possible assortment of coloured plumes on his helmet speaks.)
MERGRAVE: Once again we wait for Ruther. Was there ever a man with such capacity to lose both his quarry and himself?
(The warriors laugh. The Doctor pops up to look at them then ducks down again.
Nyssa and Tegan hide behind a tree as Ruther and his group carry the Cabinet along the base of the cliffs. He comes up behind the Doctor.)
RUTHER: This is another stranger.
(The Doctor backs away into Mergrave.)
MERGRAVE: Who are you, stranger?
DOCTOR: That's the strangest thing of all. I'm not entirely sure.

[Cliffs]

(Tegan and Nyssa are trying to scramble up between some rocks when a horn blows. Then the ground shakes and they hang on for dear life. It stops.)
TEGAN: There. Come on.

[Entrance]

(The Cabinet is carried inside.)
MERGRAVE: Bring him.
(A pair of rock doors slide closed behind them, just as Tegan and Nyssa run up.)
NYSSA: Doctor!
TEGAN: Come back! Doctor!

[Town square]

(The Doctor is pushed down onto a stone bench in an open area. There are women here, bustling around in net veils.)
RUTHER: I will give orders for the fire to be lit.
MERGRAVE: We will wait for Shardovan.
(A small quadruped is being roasted on a spit at the far end of the plaza. Okay, it's a pig.)
MERGRAVE: Well, sirs, today has been a good adventure in the wilds beyond the walls. And a quarry worth the name.
RUTHER: A fair kill, though I have seen better.
(A man comes down a stone staircase.)
SHARDOVAN: If we could cook your memories, Ruther, we would feast indeed.
(The people laugh. Shardovan walks straight to the Doctor.)
SHARDOVAN: I trust, Mergrave, you've brought us something more edible than this lifeless unfortunate?

[Entrance]

NYSSA: Closed without a trace. If we had a three micron beam wedge though.
TEGAN: Well, we haven't.
NYSSA: I said if. You taught me about if, remember?
TEGAN: It's not that sort of if. It's what we can do, with what we've got, if only we used a bit of initiative. Come on.
(Nyssa gives Tegan a leg-up the rocks by the entrance.)

[Town square]

(A woman puts a platter of food on a large wooden table.)
MERGRAVE: We should inform the Portreeve of this man's arrival.
SHARDOVAN: That has been done. But not his purpose here. May one know that?
RUTHER: He says he doesn't know who he is, or why he has come.
SHARDOVAN: Oh, I admire a man with an open mind. My own is closed upon the opinion that I am Shardovan. I have the honour to be librarian for the dwellings of Castrovalva.
DOCTOR: Librarian? Books and stuff?
SHARDOVAN: Books are the principal business of a library, sir.
DOCTOR: Then you read? You all read?
(Mergrave and Ruther remove their helmets to reveal their faces. They are not young men.)
MERGRAVE: Far too much, in my opinion. There is in this town of Castrovalva, sir, a general dedication to bodily inertia that quite defies description.
DOCTOR: Castrovalva? Yes, the place to rest.
RUTHER: Yes, and rest you shall, sir. Some refreshment, and then we must show you to your quarters.
(A woman puts more food on the table, including a pot full of celery. The Doctor takes a piece and smiles.)
DOCTOR: Definitely civilisation.

[Cliffs]

(Night is falling as Tegan and Nyssa struggle upwards.)
NYSSA: We'll never get up there.
TEGAN: Do you want to go back then?
NYSSA: We seem to be committed.

[Castrovalva]

(The Doctor walks with Shardovan and Ruther through arcades of pillars. There is no artificial lighting.)
SHARDOVAN: I understand your natural puzzlement in the matter of our outdoor garments, sir. Mergrave has devised a new religion he calls exercise.
RUTHER: In pursuit of which belief, he drives us to hunt animals in the wilds beyond the walls.
DOCTOR: The hunt. Yes, it's all coming back to me. You weren't at the hunt.
SHARDOVAN: Alas, no.

[Doctor's room]

(They go down two steps into a room where Mergrave is mixing a drink.)
RUTHER: Shardovan was detained by being longer in the body than the available habiliments could match.
SHARDOVAN: The garments with which we stir our courage to the hunt, sir, are relics of our ancestors, a smaller breed of men who, as I believe wore, down their stature with too much hunting. You will notice I am tall.
DOCTOR: I suppose that's why they made you librarian.
SHARDOVAN: Hmm?
DOCTOR: Reaching down the books from the top shelf.
(They laugh.)
MERGRAVE: The stranger is recovering his wits. A mild medicament, distilled from herbs.
DOCTOR: You're a doctor?
MERGRAVE: A master of physic, yes.
DOCTOR: Not the Doctor, I suppose? I came here to find him, I think.
RUTHER: It must be the Portreeve the stranger is in search of.
SHARDOVAN: The Portreeve, certainly. No one of us else is of the least importance.
DOCTOR: The Portreeve? A sort of magistrate?
SHARDOVAN: A man of great wisdom, sir. He reads thoroughly the books I merely rearrange. I'm sorry you will not dine with us tonight, but sleep. The meat served cold tomorrow will taste the better for it.
MERGRAVE: Good night, sir.
RUTHER: Good night.
DOCTOR: Yes, good night.
(Shardovan, Mergrave and Ruther leave. The Doctor examines the blue drink like it was a fine wine.)
PORTREEVE: Drink. It's a simple to promote healing sleep.
(A very old man is leaning on a stick. He wears a two-tiered hat.)
DOCTOR: You're the Portreeve.
PORTREEVE: Shush. It's past my bed time. If they knew I was abroad, they would press me to this feast. For me, as for you sir, sleep is sometimes better nourishment than good red meat. Please drink, sir.
DOCTOR: Yes, that is good.
PORTREEVE: Excellent. You'll very soon find the Doctor.
DOCTOR: You overheard?
PORTREEVE: I know these things.
DOCTOR: Oh?
PORTREEVE: By the simplest of means. When you visit breakfast with me tomorrow, you will see the source of what my friends are pleased to call my great wisdom. Now sir, sleep.
(The Doctor lies down on a bed.)
DOCTOR: Yes, it has been a long journey. Tell me Portreeve, off the record, will I find the Doctor here?
PORTREEVE: Oh yes, Doctor, very soon.
DOCTOR: Good.
PORTREEVE: Good night, Doctor.
DOCTOR: Good night.
(The Portreeve leaves.)
DOCTOR: Doctor? Doctor.

[Cliffs]

(Tegan and Nyssa stop to rest on a ledge high above the ground.)
NYSSA: We should have told the Doctor about Adric.
TEGAN: You said it was dangerous. He would have gone after him.
NYSSA: There might have been a chance, but now anything might have happened to the Doctor.
(A rope ladder drops down the overhanging rock.)
NYSSA: A rope ladder?

[Town square]

(The Portreeve watches the feast from a balcony above the barbeque pit. Below, Shardovan enters.)
MERGRAVE: Shardovan! More strangers have arrived. They scaled the walls.
SHARDOVAN: A new sport to replace hunting. Where are these supermen?
MERGRAVE: They're coming. I must tell the Portreeve.
SHARDOVAN: No, wait.
TEGAN: The Doctor is here.
SHARDOVAN: They're women.
TEGAN: We saw him brought in.
NYSSA: We're looking for the Doctor.
RUTHER: This is most strange. The other visitor told us the same thing.
NYSSA: Other visitor? That must be
TEGAN: The Doctor. I demand to see him.
SHARDOVAN: Very well.
MERGRAVE: But you
SHARDOVAN: Then show them to their quarters. We will not disturb the Portreeve with this news. Old men need their sleep.
(Shardovan turns to see the Portreeve above him.)
PORTREEVE: Some old men seldom sleep, Shardovan.

[Doctor's room]

(The group look at the sleeping figure from the doorway.)
NYSSA: Is he all right?
MERGRAVE: Tomorrow, he will be recovered.

[Outside the Doctor's room]

NYSSA: We have to tell him about Adric.
TEGAN: Are you sure? He's still not very strong.
NYSSA: We must. We have to think of Adric too. I know so little about telebiogenesis. If only there were some books here.
(Mergrave claps his hands to attract their attention.)
MERGRAVE: Come along.
(In the Doctor's room, Adric walks out of the wall and looks at the Doctor. Then he goes to the door and looks outside.)

[Nyssa and Tegan's room]

(The next morning, Nyssa is looking out of the window whilst Tegan sleeps on. Below in the plaza, the women are chattering and clearing away the remains of the previous night's meal. Odd scraps of conversation drift up.)
WOMAN [OC]: Don't you worry
WOMAN 2 [OC]: Yes, well, women always have to
(Nyssa leaves quietly.)

[Town square]

NYSSA: Wait! That belongs to the Doctor.
(Nyssa follows two men carrying the Zero Cabinet.)

[Doctor's room]

(Nyssa enters, and the men with the Zero Cabinet follow. She points to a blanket box by the wall and they place the Cabinet on top, then leave.)
NYSSA: Thank you.
(She walks back towards the Doctor, then spots a reflection in a cheval mirror.)
NYSSA: Adric!
ADRIC: No, don't turn around. Just listen, and listen quickly. The Master mustn't find me here.
NYSSA: He's in Castrovalva?
ADRIC: He can find me anywhere because I'm still in his power, but you mustn't let the Doctor know.
NYSSA: We have to tell him.
ADRIC: No, rescuing me can wait. Just listen. The Doctor must remain in Castrovalva until his regeneration is complete.
NYSSA: Wait, I must get Tegan.
ADRIC: No, you mustn't tell anybody you saw me. Nobody, you understand.
(Nyssa turns around. In the mirror, we see Adric get zapped with electricity, then disappear. The Doctor yawns.)
NYSSA: Doctor? DOCTOR: Nyssa. Lovely morning. I'm beginning to feel quite my old self. Or rather my new self.

[Master's Tardis]

ADRIC: No. No, I won't do it! I won't!
MASTER: But you've done it, boy. A perfect impersonation of yourself. Now we will remain untroubled by the Doctor's meddling while our plans mature.

[Portreeve's house]

(The Portreeve is sitting at the head of a long wooden table, with the Doctor on his right and the girls on his left. Two women remove the breakfast plates.)
DOCTOR: I like your Castrovalva, Portreeve. Very clever of them to have brought me here.
PORTREEVE: I fear we must be a little dull, after the habitual excitements you describe.
DOCTOR: Oh, the Ogrons and the Daleks and that. No, no, I think it does us good to be reminded the universe isn't entirely peopled with nasty creatures out for themselves.
(Shardovan enters, and a woman carrying some books.)
SHARDOVAN: The volumes you asked for, Portreeve.
PORTREEVE: Ah, thank you Shardovan. I've finished with those.
(The woman takes the three volumes at the bottom of the table.)
SHARDOVAN: Ah, very well.
PORTREEVE: Let me introduce, Tegan and Nyssa, Shardovan the librarian.
NYSSA: There is a library.
SHARDOVAN: Which I hope you will visit.
NYSSA: I'd love to see it now.
PORTREEVE: Then you shall. There's something I want to show the Doctor.
(Nyssa, Tegan and Shardovan leave. The Doctor gets up to look at a large tapestry of leaves and flowers that fills an alcove.)
DOCTOR: Whoever did this certainly has a way with needle and thread.
PORTREEVE: Remarkable, isn't it?
(The Portreeve looks at it through a magnifying sheet on the end of his walking stick.)
DOCTOR: This device you mentioned
PORTREEVE: It stands before you, Doctor. I've returned it to its state of yesterday, by way of demonstration.
(In the middle of the tapestry we see Tegan and Nyssa with the Zero Cabinet.)

[Outside the library]

(Shardovan leads Nyssa and Tegan up the stairs to the battlements.)
NYSSA: Do you have any books on telebiogenesis?
SHARDOVAN: The technical section is not large, you will find, but you are welcome to browse.

[Portreeve's house]

DOCTOR: Fascinating demonstration, Portreeve. How often do the pictures renew themselves?
PORTREEVE: Life here in the main is very slow and unremarkable. Only an occasion, like your visit, disturbs the cycles enough to register on the tapestry.
(The image is of Nyssa and Tegan carrying the Cabinet through the woodlands.)
DOCTOR: Some form of fast particle projection, I suppose.
PORTREEVE: Our forbears had many skills, now forgotten.
DOCTOR: Indeed.
PORTREEVE: Oh, there's no doubt some complexity behind it, but in view of what you told me you had better avoid such things until you are restored.
DOCTOR: You know, I had no idea I was putting them to so much trouble. It's a very long way for three young people to carry me.
PORTREEVE: Three, Doctor?
DOCTOR: Yes. Er, Tegan, Nyssa and, er, Tegan. No, that's silly. Er, Nyssa, Tegan and Nyssa. Nyssa, Tegan. You know, I'm sure there's someone missing.
(The Portreeve is starting to look a little familiar around the eyes.)

[Outside the Library]

(Tegan and Nyssa come out carrying armfuls of books.)
TEGAN: These aren't going to help us much with Adric.
NYSSA: A small technical section. There weren't any technical books at all.
TEGAN: Well, let's read the history of Castrovalva. Might tell us why.
NYSSA: Let's take them back to the Doctor's room.
(Shardovan watches them leave.)

[Town square]

(Women are washing cloths in a tub by the central fountain whilst a girl bounces a ball. The Doctor enters, deep in thought.)
DOCTOR: One, two. Good day. One, two. No, no, no, no.
(He sits on some steps and the girl comes over.)
DOCTOR: One, two.
CHILD: Three, sir.
DOCTOR: What?
CHILD: Three, sir, is what comes after two.
DOCTOR: Do you know, that's exactly what I thought.
CHILD: And then four and then five and then six and then seven
DOCTOR: Stop, please. You're making me dizzy. We'll have to give you a badge for mathematical excellence. (lightbulb moment) Adric. Adric!

[Doctor's room]

(Nyssa and Tegan are reading when the Doctor bursts in.)
TEGAN: The history of Castrovalva's fascinating.
DOCTOR: No time for that. Where is he?
TEGAN: Sorry?
DOCTOR: Adric!
TEGAN: You told him.
NYSSA: No, Adric told me not to.
DOCTOR: Adric told you?
TEGAN: Adric?
NYSSA: I'm, I'm so sorry, Doctor, but
DOCTOR: Please, never mind about the apologies. I think it's time I heard all about this.

[Outside the Library]

SHARDOVAN: What, going so soon?
MERGRAVE: Whether for some offence we've given or just a sudden fancy, I cannot say.
SHARDOVAN: He cannot leave. He must not.
MERGRAVE: He seems firm in his intent.
SHARDOVAN: Then we must intervene.

[Castrovalva]

(The trio walk along an upper balcony next to stairs leading downwards.)
DOCTOR: The Tardis.
NYSSA: The Zero cabinet.
DOCTOR: We can't go through all that again.
TEGAN: But once you get outside the walls
DOCTOR: Well, we'll just have to hope, won't we?

[Town square]

(The women are still washing and folding.)
DOCTOR: Which is the quickest way out of here?
(Everyone points in a different direction.)
DOCTOR: Yes, well that's democracy for you. Come on.

[Castrovalva]

(The Doctor heads down a set of stairways.)
NYSSA: I don't remember this.
DOCTOR: Never mind, come on. (And downwards.)
DOCTOR: I always did have a terrible sense of direction. Still as long we keep going down.
TEGAN: It's impossible!
(They are looking down into the - )

[Town square]

RUTHER: Oh, I beg you, Doctor, reconsider this hasty departure.
MERGRAVE: For reasons of health, if not of courtesy.
DOCTOR: Sorry. No time. Must dash. Come back later. Where does this lead?
RUTHER: Out, sir, if you insist.
DOCTOR: Thank you.

[Castrovalva]

(Out onto a set of stairs that leads to the balcony overlooking the plaza. Town planning by Maurits Cornelis Escher? He made a lithograph called Castrovalva in 1930. Click here if you want to see it.)
TEGAN: That wretched square again. Doctor, what's happening?
DOCTOR: Shush. Concentrate. This could be serious.
NYSSA: It's as if space had folded in on itself.
DOCTOR: Very like it. Quick. There may still be time to reverse the sense!
(He runs back up the stairs.)

[Town square]

(The Doctor is stopped by Shardovan on the next set of stairs.)
SHARDOVAN: Doctor, what is the occasion of this haste?
(Tegan and Nyssa sort of catch the Doctor as he steps backwards, doubling over.)

[Outside the Doctor's room]

NYSSA: It's affecting him, some very complex spatial disturbance.
TEGAN: What is it, Doctor?
DOCTOR: Castrovalva, folding in on itself deliberately.
NYSSA: Come on, this way.
TEGAN: The Doctor's room.
NYSSA: Oh, thank goodness. We must get him back in the Zero cabinet immediately.

[Doctor's room]

TEGAN: The Zero cabinet. It's gone.
(Only one piece of Tardis with three roundels in it remains on the blanket box. The Doctor looks out of the window.)
DOCTOR: Recursive occlusion. Someone's manipulating Castrovalva. We're caught in a space-time trap!
(The view out of the window is of multiple views of the city at the same time.)

Part Four

[Doctor's room]

(The Doctor clutches his head in pain. Nyssa and Tegan close the shutters on the chaos outside.)
DOCTOR: I'm perfectly all right. We have got to find out what's causing the occlusion. Follow me!
(He sits on his bed.)
DOCTOR: Please find the Zero Cabinet.
NYSSA: The Portreeve. He'll help us. Wait here, Doctor.
DOCTOR: Be careful. If I'm right, the occlusion won't be dangerous to you at this moment. You're only trouble will be finding the way. Quickly!
(Tegan and Nyssa leave. The Doctor grabs the mirror and looks at the window.)

[Castrovalva]

(Ruther leads Tegan and Nyssa down some stairs.)
RUTHER: You should prepare yourselves for disappointment. It is unusual for the Portreeve to grant two audiences on the same day.
TEGAN: Just take us to him.

[Doctor's room]

(The Doctor is exhausted from moving the cheval mirror to face outwards through the window. He lies on his bed and picks up one of the books the girls brought from the library.)
DOCTOR: Must be about five hundred years old.
(He finds a loose piece of notepaper inside it.)
DOCTOR: Now that's odd. That's very odd indeed.
(The door opens and the Doctor hides the note in his coat. Mergrave puts his head round the door.)
DOCTOR: Mergrave. Just the chap. There's something you can do for me.

[Castrovalva]

TEGAN: That square again.
NYSSA: We keep coming back to it.
RUTHER: Of course.
TEGAN: But you must see that there's something going wrong here?
RUTHER: There are, as you have observed, steps that rise from the square and others that lead downwards from it, while other walks debouch laterally. An equitable arrangement, surely, allowing for much variety of movement.
TEGAN: You're not going to tell me you don't realise
RUTHER: Ah, there is an exemplary vista from here.
(He looks through a small telescope.)
TEGAN: He must know. They're all in this together.
NYSSA: They would be if they were part of the recursion.
RUTHER: Here. Fine view down into the water tower.
NYSSA: Wait a minute.
(Nyssa takes the telescope and scans the square. She sees Shardovan entering.)
NYSSA: Look.
TEGAN: What is it?
(The women are using the Zero Cabinet as a washtub.)
TEGAN: So that's where it got to.

[Doctor's room]

(The Doctor is reading when Margrave enters.)
MERGRAVE: Here are the other fifteen volumes. Put them down there.
(The women, of course, are doing the actual carrying. They put them on the blanket box.)
DOCTOR: Well done, Margrave.
MERGRAVE: All right, run along.
(The women leave.)
DOCTOR: You know, I'm very fond of history, but I don't usually get much time for reading.
(Mergrave goes to move the mirror.)
DOCTOR: No! Please. It's backed with silver. Helps to keep it out.
MERGRAVE: It? And what, sir, is it?
DOCTOR: Precisely what I'm trying to find out. Tell me, Mergrave, what do you see out of the window?
MERGRAVE: Well, sir, the town square, the library, the Portreeve's house and my own pharmacy. In fine, sir, the dwellings of Castrovalva.
DOCTOR: And it all makes sense to you?
MERGRAVE: Strange question. Shardovan has asked the same.
DOCTOR: Shardovan.
(Mergrave pours another dose of his blue tonic into a glass.)
MERGRAVE: He too can be a little fevered in his imaginings. This will dispel your fatigue.
(The Doctor nearly drinks it.)
DOCTOR: How do I know you're telling the truth?
MERGRAVE: Because, sir, I maintain I am, and I am a man of my word.
DOCTOR: A perfect example of recursion, Mergrave. And recursion is exactly what we're up against. Draw me a square, large as you can.
(Mergrave takes a piece of chalk from the Doctor and starts to draw on the back of the mirror. It is a square.)
DOCTOR: Good. Now, in the square, a rough map of Castrovalva.

[Town square]

(The women are emptying the Cabinet.)
TEGAN: You hid this deliberately.
SHARDOVAN: Assuredly, ma'am, no impropriety was intended.
TEGAN: You're all part of this. It's a conspiracy.
RUTHER: They have formed the suspicion that the Doctor has been ensnared.
SHARDOVAN: Ah. They cannot think that.
NYSSA: Come on. We must get this back to the Doctor straightaway.
(Tegan and Nyssa carry the Cabinet away. Ruther follows them.)

[Doctor's room]

(The map is progressing.)
DOCTOR: Now, the library, the square, the Portreeve's house. Now, where's your pharmacy?
MERGRAVE: Up here, sir. And down here. And round here. And along here also.
(Crosses on the outside lines of the map. Oops.)
DOCTOR: Four pharmacies in a small place like this?
MERGRAVE: No, sir. I have but one.
DOCTOR: You positioned it four times.
MERGRAVE: It may be approached, sir, by many different routes.
DOCTOR: Hmm.
(He drinks the tonic.)
DOCTOR: Valeriana officinalis centiculare europea. And just a hint of rosemary.
MERGRAVE: You understand medicine, Doctor.
DOCTOR: Not as well as you. But I'm afraid one of us is deluded about geography.

[Outside the Doctor's room]

(Nyssa knocks on the door.)
NYSSA: Doctor?
DOCTOR [OC]: Yes, yes, come in.

[Doctor's room]

TEGAN: We found it, and no thanks to these Castrovalvan people. They kept leading us round and round and back to the square.
DOCTOR: Well, that's Castrovalva, not Ruther. I suppose you know the whereabouts of the Portreeve's house.
RUTHER: Nothing is more certain, sir.
DOCTOR: Well put. Show us on the map.
RUTHER: This is the Portreeve's house, along here, down there, (pause) round there.
MERGRAVE: The Doctor has been explaining to me. I almost grasp it.
RUTHER: There is something amiss with the map.
DOCTOR: There is something amiss with Castrovalva, but because your perception is part of it, you cannot see it.
RUTHER: I am a rational man, sir. Explain this interesting idea.
DOCTOR: Yes, well, I'm afraid that would take some doing.
NYSSA: Doctor, the Cabinet.
DOCTOR: Yes, yes, in a minute. This library of Shardovan's, are all the books like this?
NYSSA: Yes, why?
DOCTOR: These volumes chronicle the rise of Castrovalva out of an alliance of warring hunters twelve hundred years ago. Or purport to chronicle.
MERGRAVE: Purport, you say?
RUTHER: That, sir, is our official history.
MERGRAVE: From Castrovalva's first beginnings to the present day.
DOCTOR: Yes, well, I'm no expert, but I have the strongest possible hunch that these are forgeries.
RUTHER: What do you say, sir?
DOCTOR: Oh, the threads, the bindings, the paper, are as near the real thing as may be, but the contents are faked.
NYSSA: How can you tell?
DOCTOR: There is something we're all overlooking.
NYSSA: Yes? What, Doctor?
DOCTOR: I don't know. I'm overlooking it, too.
(He takes the note out of his coat.)
DOCTOR: But I'm certain the whole history's been invented.
TEGAN: By Shardovan.
NYSSA: But why? To hide something?
TEGAN: Something about the real history. Doctor?
DOCTOR: If there ever was a real history.
(Voices can be heard outside.)
MERGRAVE: This noise is not acceptable.

[Outside the Doctor's room]

(There is a crowd of women outside.)
MERGRAVE: The visitor is weaker, but receiving our best attention. But you must remain quiet as noise causes him great distress.
WOMAN: (sotto) Yes, okay.

[Doctor's room]

(The Doctor is in the Cabinet, and Ruther is reading the note.)
RUTHER: This is Shardovan's hand. The librarian.
DOCTOR: Shardovan. I thought as much. I must see the Portreeve.
MERGRAVE: I'm sure, given your condition, the Portreeve will be happy to see you.
TEGAN: We'll carry him there.
MERGRAVE: As you wish.
TEGAN: Would you mind waiting outside?
NYSSA: We'll bring him out in a minute.
MERGRAVE: Never been treated like this before.
RUTHER: By a woman.
(Tegan ushers them out.)
DOCTOR: One little suggestion.

[Outside the Doctor's room]

(The crowd is still there, whispering amongst themselves.)
MERGRAVE: I wish I could be of more help.
TEGAN: It's a complicated thing, this recursion business.
MERGRAVE: Please, let us have quiet here.
SHARDOVAN: Why are all these women here? Is this a holiday?
MERGRAVE: The Doctor is most unwell.
(Tegan goes back inside the room.)
RUTHER: It's been agreed to carry him to the Portreeve. We must all help.
SHARDOVAN: Very well.
(Tegan and Nyssa come out carrying the Zero Cabinet.)
SHARDOVAN: Allow me to assist you.
TEGAN: No, keep away.
SHARDOVAN: Please, I insist I do my small part.

[Town square]

(So the procession is Shardovan and Mergrave carrying the front of the Cabinet, with Ruther and another man carrying the back, followed by the women and Nyssa, with Tegan bringing up the rear. She cuts across the square to get ahead of them.)
TEGAN: Excuse me. I am responsible for the Doctor.
(Shardovan gives up his corner, and Nyssa comes next to Tegan.)
MERGRAVE: This way.
(The procession carries on, but Shardovan hangs back. A hand beckons to him from behind a pillar. It's the Doctor.)
TEGAN: The Doctor can't be levitating. He's so heavy.
(Nyssa whispers in Tegan's ear.)
TEGAN: Then?
NYSSA: (sotto) The history of Castrovalva.
TEGAN: What, all thirty volumes?
(The procession leaves.)
DOCTOR: You're the man I want.
SHARDOVAN: Explain yourself, sir.
DOCTOR: You're the only man here who could not be persuaded to join the hunting ritual.
SHARDOVAN: Ah. My natural indolence would not permit it.
DOCTOR: Your intelligence would not permit it. You suspected the whole tradition was invention from beginning to end and here's the proof. Your annotations of the histories.
SHARDOVAN: Ah. Mere fancies, sir. Notes for a fiction I had a mind to write.
DOCTOR: Hmm. The fiction of Castrovalva. A civilisation evolving out of tribal warfare into an ideal community. It is a fiction, and the thing that confirms it
SHARDOVAN: Well, sir?
DOCTOR: Oh, I know it. It's on the tip. It's on the tip of my mind. The books are five hundred years old at least, but
SHARDOVAN: The books are old, but they chronicle the rise of Castrovalva up to the present day.

[Portreeve's house]

(The Zero cabinet is placed on the dining table.)
MERGRAVE: Portreeve, the visitor's strange illness has progressed beyond my power to heal.
RUTHER: We have come for your help.
PORTREEVE: Please, not my help. This is a matter for the tapestry.

[Castrovalva]

DOCTOR: Don't tell me you're lost, too?
SHARDOVAN: No, but as you guessed, Doctor, we people of Castrovalva are too much part of this thing you call the occlusion.
DOCTOR: But you do see it? The spatial anomaly.
SHARDOVAN: With my eyes, no. But in my philosophy. This way. I know a back way.

[Portreeve's house]

PORTREEVE: The Doctor has journeyed dangerously to honour us here in Castrovalva, and look at the outcome.
MERGRAVE: Portreeve, should we not begin?
PORTREEVE: Everything's in hand. With this tapestry and with patience, there's nothing one cannot achieve. Nothing, Doctor, in this world or in any other. The tapestry has the power to build and hold in space whole worlds of matter.
(An image of Castrovalva appears in the middle of the tapestry.)
PORTREEVE: But I've contented myself with one small, simple town.
(The Portreeve straightens up. His hair turns from white to black, the beard disappears and the voice strengthens.)
MASTER: For the final meeting of the Doctor with his Master! Bwahahahaha!

[Castrovalva]

(Shardovan points up at a round window. The Doctor becomes dizzy.)
SHARDOVAN: Doctor.
DOCTOR: We must be very close to whatever he's using to power all this. Come on, we'll have to hurry. You're a good tall chap.
(Shardovan gives the Doctor a leg up to climb the wall.)

[Portreeve's house]

MASTER: I have waited patiently with this trap of mine. My Castrovalva.
NYSSA: But there is a real Castrovalva. It's mentioned in the Tardis databank.
MASTER: The boy Adric entered it there at my command.
NYSSA: Adric.
TEGAN: Where is he? What have you done with him?
MASTER: The boy is nothing. I want the Doctor. One long last look before I destroy him utterly.
(The Master tries to pry open the Zero Cabinet while the Doctor tries to open the round window from the outside. That image is also on the tapestry, and Tegan and Nyssa see it. The Master uses his Tissue Compressor on the Cabinet.)
NYSSA: You've got to stop him. He's the Master!
(Glass breaks.)
MASTER: What was that? Go on, find out.
(Mergrave and Ruther leave.)

[Upstairs in the Portreeve's house]

The Doctor and Shardovan climb through the window onto a small balcony at the top of a flight of stairs.)
SHARDOVAN: Now, Doctor
DOCTOR: Shush!

[Portreeve's house]

MASTER: Open this for me!
NYSSA: Don't you understand anything about zero structures? The internal interfaces are bonded by strong-force interaction. The surfaces can only be separated from inside the Cabinet.
MASTER: Don't try to make a fool of me.
(The Master takes an iron from the stand by the fireplace to try and prise it open.)

[Upstairs in the Portreeve's house]

MERGRAVE: Doctor?
RUTHER: This is beyond all sense.
MERGRAVE: You must come along with us.
SHARDOVAN: No. You must spare the Doctor.
RUTHER: No, Shardovan. He has betrayed the Portreeve.
SHARDOVAN: My dear friends, it's we who've been betrayed.
DOCTOR: Listen carefully. This man you know as Portreeve is the most evil force in the universe. You have got to help me defeat him. Got to, do you understand?
SHARDOVAN: You do have doubts. We've spoken of it often.
DOCTOR: Well, say something, please!
SHARDOVAN: Shush.
DOCTOR: Yes would be best.

[Portreeve's house]

MASTER: I have you in my power absolutely, but I will see your face before I destroy you forever.
(Mergrave and Ruther quietly approach the Master as he struggles to open the Zero Cabinet.)
TEGAN: That wretched tapestry. He'll spot the Doctor any minute now.
MASTER: Well? Well, speak. I gave you tongues.
MERGRAVE: You are not the Portreeve.
MASTER: Someone's been tampering with your perception threshold.
RUTHER: You are not the Portreeve. I believe the visitor.
(The Master turns round and finally sees the Doctor on the tapestry.)
MASTER: A trick! The Doctor's here.
DOCTOR [OC]: Are you sure of that, Master?
MASTER: Enough of your deceptions!
(The Master drags the Zero Cabinet from the table. It breaks open when it hits the floor.)
MASTER: Where are you? I'll fetch you out wherever you are.
NYSSA: The tapestry, look!
(It fades to reveal Adric hanging in the web. The Doctor rushes down a flight of stairs.)
TEGAN: But Doctor, it's
DOCTOR: I know, I know. Stay back.
(The Doctor rips down the tapestry. Shardovan stays upstairs in the shadows.)
DOCTOR: So that's how you're sustaining Castrovalva.
MASTER: My own adaptation of the block transfer computation. Since we last me, Adric's mathematical powers have been put to lively use.
DOCTOR: Deadly, you mean.
MASTER: That, too. You were wise to deter your young friends from approaching. The hadron power lines are lethal to the touch.
DOCTOR: All right, Master. It's me you want. Let the boy go.
MASTER: Yes, a trap has now been sprung. We can begin to dispose of all the bait.
(Ruther picks up a fire iron to hit the Master, then freezes and vanishes.)
DOCTOR: There was no call for that.
MASTER: I populated Castrovalva. I will dispose of these creatures as I choose.
(Up above, Shardovan has hooked a metal chandelier with a candle snuffer, and is pulling it towards him.)
DOCTOR: Unless you let every one of them go now
MASTER: Well, Doctor?
(The Doctor grimaces in pain then the Master points upwards. Shardovan is preparing to swing on the chandelier.)
DOCTOR: Shardovan, get back!
MASTER: Don't touch the web. It's holding Castrovalva in balance. You do not have the will!
SHARDOVAN: You made us, man of evil, but we are free.
(Shardovan swings across the room and into the web.)
MASTER: My web!
(Adric is freed in a flurry of sparks.)
MASTER: My web!
(The Doctor dashes to help Adric. The Master ducks into the fireplace and pulls down a grill. A Tardis engine starts up.)
NYSSA: The Master! Look!
TEGAN: The fireplace. It's his Tardis.
(The fireplace dematerialises, leaving a plain wall. The Doctor and Adric come into the middle of the room.)
NYSSA: Shardovan?
DOCTOR: He gave his life to help us.
TEGAN: The Master has escaped.
DOCTOR: So must we. Without the web to support it, the local space will fold up into itself. Come on!

[Town square]

(The citizens of Castrovalva are running to and fro in a pixilated town.)
NYSSA: Where are we going?
DOCTOR: It still makes sense to Mergrave. Stay behind him.
(Mergrave sees calm normality.)
MERGRAVE: This way.
(They run along one balcony then back upside down beneath it.)
DOCTOR: The square again.
NYSSA: The Master's Tardis.
(The fireplace is in the square.)
DOCTOR: It couldn't take off. Space is squeezing in too fast.
TEGAN: We're trapped.
NYSSA: How do we get out?
DOCTOR: It can't collapse without causing a breach somewhere.
MERGRAVE: There is nothing but confusion in my eyes now.
ADRIC: I can see.
DOCTOR: Adric created it. Which way?
ADRIC: What exactly am I looking for, Doctor?
DOCTOR: Anything you don't recognise as Castrovalva.
ADRIC: Over there. The hillside.
DOCTOR: Follow Adric. Hold on to each other.

[Tunnel]

(Adric leads them into a rock tunnel leading downwards.)
ADRIC: This is it. This is the way.
DOCTOR: Mergrave.
MASTER [OC]: My web!
MERGRAVE: Goodbye, Doctor.
MASTER: Bring it to me, boy. My web!
(Mergrave wrestles with the Master in the tunnel.)
ADRIC: Doctor, quickly, we've got to leave before it closes again.

[Entrance]

TEGAN: Doctor! Adric! Please hurry!

[Tunnel]

(Other Castrovalvans are pulling at the Master from the other side.)
DOCTOR: Mergrave, we have got to leave.
MASTER: No! You can't beat me! Traitors!
(Adric pulls the Doctor outside and the doors close. The screaming Castrovalvans continue to grapple with the Master.)

[Woodland]

(The Doctor, Tegan, Nyssa and Adric stop on the path and look back at the cliffs.)
NYSSA: It's gone. Gone forever.
ADRIC: And the Master?
DOCTOR: Let's hope so.
(They jog towards the Tardis.)
DOCTOR: One, two, one, two, one, two, one, two, one, two, one, two. All right, rest. Deep breaths. Well done, Adric.
TEGAN: Why couldn't we just walk?
DOCTOR: Got to be fit to crew the Tardis. Trim Time Ship and a ship-shape team.
(He fastens a piece of celery to his lapel, then sees the top of the Tardis down the slope.)
DOCTOR: Who landed this?
TEGAN: I did, Doctor.
DOCTOR: You flew the Tardis?
TEGAN: I followed the instructions in the computer.
DOCTOR: There aren't any.
TEGAN: But
DOCTOR: It was a projection.
NYSSA: As Adric was, in the Zero Room.
TEGAN: So I didn't fly it?
DOCTOR: Adric pre-programmed it. Whatever you did to the console, we'd have ended up at Castrovalva.
TEGAN: Oh, how disappointing.
DOCTOR: The Master leaves nothing to chance.
(They walk down the slope.)
DOCTOR: Adric?
(Adric starts to climb to the Tardis doors.)
NYSSA: Are you sure you're up to flying the Tardis?
DOCTOR: Oh, I think so. In fact, I feel quite like my old self. Well. 
TEGAN: Yes?
DOCTOR: Well, whoever I feel like, it's absolutely splendid. Let's go.
(He helps Nyssa and Tegan climb into the tilted Tardis, then follows them. The Tardis dematerialises.)