[Central dome]

(An image of a young woman holding a baby on her lap comes up through the static.)

EMILY [on monitor]: Hello, Mum. Susie says hello, don't you, sweetheart? That's it. Give a little wave. Er, oh, what was I going to say? Uncle Soon called in, he says hello. He keeps saying, you must be missing her. I said, she's been gone for over two years now, I'm getting used to it.

(Static.)

EMILY [on monitor]: Oh, no, it's breaking up. It must be the solar flares.

ADELAIDE: Talk faster.

EMILY [on monitor]: About the deposit on the house. Oh, er, I've spoken to the bank

(Transmission lost.)

[Mars]

(The Tardis materialises and the Doctor steps out, wearing a red spacesuit.)

DOCTOR: The red planet.

[Central dome]

(A man in a white spacesuit leaves an airlock carrying a device with a solar panel attached to the tripod.)

ED [OC]: Sun sets in ten minutes, Yuri. You're going to lose the light.

MIA: That's it. Got you on External Ten.

YURI [on monitor]: Almost there. That's the radial clamp down. One more thing.

ED: Get back inside, you're using power and oxygen.

[Outside the airlock]

YURI: Oh, hold on. Get this on camera. What do you think?

(He holds up the solar panel. It has No Trespassers written on it.)

[Central dome]

MIA: Hey, looks good. Nice one, Yuri.

ED: You wasted an entire solar panel just to make that.

YURI [on monitor]: Oh, lighten up. It's a joke.

ED: We come all this way to an empty planet, untouched by civilisation, and what do we do? Put up cheap jokes. That's not funny, that's pollution.

ADELAIDE: Having fun?

ED: I was just telling him.

ADELAIDE: I expect better of you, Ed. Now get back to work, all of you.

[Mars]

(The Doctor looks over a crater rim and down onto the Base with its five outlying domes and shuttle pad connected to the central dome by modular walkways.)

DOCTOR: Oh, beautiful.

(Something jabs him in the back.)

GADGET: Rotate slowly.

(He does. It is a little robot.)

GADGET: You are under arrest for trespassing. Gadget gadget.

[Central dome]

(Adelaide points a gun at the Doctor, who is now out of his spacesuit.)

ADELAIDE: State your name, rank, and intention.

DOCTOR: The Doctor. Doctor. Fun.

(A dark-skinned man runs in.)

TARAK: What the hell? It's a man. A man on Mars. How?

STEFFI: He was wearing this thing. I have never seen anything like it.

TARAK: What did Mission Control say?

STEFFI: They're out of range for ten hours with the solar flares.

ADELAIDE: If we could cut the chat, everyone.

DOCTOR: Actually, chat's second on my list, the first being gun pointed at my head. Which then puts my head second and chat third, I think. Gun, head, chat, yeah. I hate lists. But you could hurt someone with that thing. Just put it down.

ADELAIDE: Oh, you'd like that.

DOCTOR: Can you find me someone who wouldn't?

ADELAIDE: Why should I trust you?

DOCTOR: Because I give you my word. And forty million miles away from home, my word is all you've got.

ADELAIDE: Keep Gadget covering him.

GADGET: Gadget gadget.

DOCTOR: Oh right, so you control that thing. Auto-glove response.

ROMAN: You got it. To the right.

GADGET: Gadget gadget.

ROMAN: And to the left.

DOCTOR: It's a bit flimsy.

GADGET: Gadget gadget.

DOCTOR: Does it have to keep saying that?

ROMAN: I think it's funny.

DOCTOR: I hate funny robots.

MAGGIE [OC]: Excuse me, boss. Computer log says we've got an

[Biodome]

MAGGIE: Extra person on site. How's that possible?

ADELAIDE [OC]: Keep the Biodome closed.

[Central dome]

ADELAIDE: And when using open comms, you call me Captain.

MAGGIE [OC]: Yeah, but

[Biodome]

MAGGIE: Who is it? Disconnected. She's cut me off. Can you believe her? It's like we're just gardeners.

ANDY: As long as they leave us alone, that's fine with me. Oh, you beauties. Look at this.

(He holds off a couple of carrots.)

MAGGIE: Better start planting some more if there's an extra mouth to feed.

ANDY: The very first garden off Earth. Everything brand new. Eden. That's what we should've called this place.

(He washes the carrots and takes a bite.)

MAGGIE: It's the Philippines. I bet. If there's someone else on Mars, it's got to be the Philippines. All those stories about them building a rocket. Adelaide's going to love that. Stealing her thunder. Mind you, worth it to see her face.

(Behind her back, Andy starts jerking.)

MAGGIE: Or it could be the Spanish. They kept that Spacelink project under wraps. Didn't your sister work for them? Are you all right, mate? Come on, stop mucking about. Andy? Are you okay?

(Andy turns around. His eyes are white, the skin around his mouth has big cracks in it and water is dribbling out. Margaret screams.)

[Central dome]

ED: He can't be a World State flight, because we'd know about it. Therefore, he's got to be one of the independents, yeah? Was it the Branson inheritance lot? They've talked about a Mars shot for years.

DOCTOR: Right, yes, okay, you got me. So, I'm the Doctor, and you are?

ADELAIDE: Oh, come on. We're the first off-world colonists in history. Everyone on planet Earth knows who we are.

DOCTOR: You're the first? The very first humans on Mars? Then this is

BOTH: Bowie Base One.

DOCTOR: Number one. Founded July 1st, 2058. Established Bowie Base One in the Gusev Crater. You've been here how long?

(The Doctor remembers an article about it.)

ADELAIDE: Seventeen months.

DOCTOR: 2059. It's 2059, right now. Oh! My head is so stupid. You're Captain Adelaide Brooke. And Ed. You're Deputy Edward Gold. Tarak Ital, MD. Nurse Yuri Kerenski. Senior Technician Steffi Ehrlich. Junior Technician Roman Groom. Geologist Mia Bennett. You're only twenty seven years old.

(And his memories say they all died in 2059.)

ADELAIDE: As I said, Doctor, everyone knows our names.

DOCTOR: Oh, they'll never forget them. What's the date, today? What is it? Tell me the exact date.

ADELAIDE: November 21st, 2059.

(Bowie Base destroyed. World in mourning. Nuclear blast crater - November 21 2059.)

DOCTOR: Right. Okay, fine.

STEFFI: Is there something wrong?

MIA: What's so important about my age?

DOCTOR: I should go. I really should go. I'm sorry. I'm sorry with all of my hearts, but it's one of those very rare times when I've got no choice. It's been an honour. Seriously, a very great honour to meet you all. The Martian pioneers.

(He shakes all their hands, except Roman who has the auto-gloves on, so he pads Gadget instead.)

DOCTOR: Oh, thank you. Ah.

GADGET: Gadget gadget.

(He salutes Adelaide.)

DOCTOR: Thank you. There's the other two. Hold on. Margaret Cain and Andrew Stone.

ED: Maggie, if you want to meet the only new human being that you're going to see in the next five years, better come take a look.

(A roar comes over the speaker.)

MIA: What was that?

DOCTOR: Oh, I really should go.

ED: This is Central. Biodome report immediately.

ADELAIDE: Show me the Biodome.

ED: Internal cameras are down.

ADELAIDE: Show me the exterior.

(The lights are going out in the biodome.)

ADELAIDE: I'm going over. Doctor, with me.

DOCTOR: Yeah, I'm sorry. Er, I'd love to help, but I'm leaving right now.

ADELAIDE: Take his spacesuit, lock it up. This started as soon as you arrived, so you're not going anywhere except with me.

[Tunnel 1]

GADGET: Gadget gadget.

ADELAIDE: What's so important about Mia's age? You said she's only twenty seven. Why does it matter? What did you mean?

DOCTOR: Oh, I just open my mouth and words come out. They don't make much sense.

TARAK: Telling me.

DOCTOR: Thank you, Doctor.

TARAK: Any time, Doctor.

GADGET: Gadget gadget.

[Central dome]

(Gadget is relaying the scene back.)

DOCTOR [on monitor]: I hate robots. Did I say?

ROMAN: Yeah, and he's not too fond of you. What's wrong with robots?

[Tunnel 1]

DOCTOR: It's not the robots, it's the people. Dressing them up and giving them silly voices. Like you're reducing them.

ROMAN [OC]: Yeah. Friend of mine

[Central dome]

ROMAN: She made her domestic robot look like a dog.

[Tunnel 1]

DOCTOR: Ah well, dogs. That's different.

ROMAN [OC]: But I adapted Gadget out of the

[Central dome]

ROMAN: Worker drones. Those things are huge. They built this place when the shell was lowered down from orbit. They've got a strength capacity of fifteen tons.

ADELAIDE [OC]: The channel is open for essential

[Tunnel 1]

ADELAIDE: Communications only.

[Central dome]

ROMAN: Sorry. Love those drones.

[Tunnel 1]

DOCTOR: I've read all that stuff about you, Captain Adelaide. But one thing they never said. Was it worth it, the mission?

ADELAIDE: We've got excellent results from the soil analysis.

DOCTOR: No, but all of it. Because they say you sacrificed everything. Devoted your whole life to get here.

ADELAIDE: It's been chaos back home. Forty long years. The climate, the ozone, the oil apocalypse. We almost reached extinction. Then to fly above that, to stand on a world with no smoke, where the only straight line is the sunlight? Yes. It's worth it.

DOCTOR: Ah. That's the Adelaide Brooke I always wanted to meet. The woman with starlight in her soul.

ADELAIDE: What's that?

(They run to a figure lying on the floor.)

ADELAIDE: It's Maggie.

DOCTOR: Don't touch her!

TARAK: I know the procedure. Maggie, can you hear me? It's Tarak. Maggie? It's okay, she's still breathing. She's alive. Yuri, I've got Margaret Cain, head trauma. I need a full medpack.

[Sickbay]

YURI: I've got it. Medpack on its way.

[Central dome]

ED: I'm going to help!

STEFFI: In the absence of the Captain, you're in charge, sir! You've got to stay in the Dome.

(Too late, he's gone.)

[Tunnel 1]

(Ed and Yuri arrive at the double with a stretcher.)

DOCTOR: Don't touch her. Use the gloves.

TARAK: Do what he says. Get her to Sickbay. Put her in isolation.

ADELAIDE: We're going on to the Biodome. Tarak, with me. Yuri can take care of her. Ed, go back. Gadget, stand guard. Keep an eye on this area.

GADGET: Gadget gadget.

ED: Captain, you're going to need me. Andy is the only other crew member out here, and if that wasn't an accident, then he's gone wild.

ADELAIDE: You've deserted your post. Consider that an official warning. Now get back to work. Doctor.

[Central dome]

STEFFI: Captain, that sound we heard from the Biodome. I've run it through diagnostics. According to the computer, it's, it's Andy.

[Biodome airlock]

STEFFI [OC]: It registers as the voice print of Andy Stone.

ADELAIDE: Understood. Double check, thanks.

TARAK: Air pressure stabilised.

[Biodome]

ADELAIDE: Andrew? Andrew Stone? It's Captain Brooke. Andy, report. I need to see you. Where are you?

(The Doctor sonics a computer terminal and the lights come back on.)

DOCTOR: There you go.

ADELAIDE: What's that device?

DOCTOR: Screwdriver.

ADELAIDE: Are you the Doctor or the janitor?

DOCTOR: I don't know. Sounds like me. The maintenance man of the universe.

ADELAIDE: You stay with me. Don't step out of my sight. Tarak, go to External Door South. Make sure it's intact.

TARAK: Yes, ma'am.

DOCTOR: Quite an achievement. First flower on Mars in ten thousand years. And you're growing veg!

ADELAIDE: It's that lot. They're already planning Christmas dinner. Last year it was dehydrated protein, this year they want the real thing.

DOCTOR: Still, fair enough. Christmas.

ADELAIDE: If we must.

DOCTOR: You've got birds!

ADELAIDE: It's part of the project, to keep the insect population down.

DOCTOR: Good sign.

ADELAIDE: In what way?

DOCTOR: Well, they're still alive.

YURI [OC]: Captain, good news.

[Sickbay]

YURI: It's Maggie. She's awake. She's back with us. Hey. How are you, soldier? Just take it easy. Can you remember what happened?

MAGGIE: I was just working. Then I woke up here.

[Biodome]

ADELAIDE: What about Andy? We can't find him.

[Sickbay]

ADELAIDE [OC]: Was he all right?

MAGGIE: I don't know. I just

ADELAIDE [OC]: If you remember anything, let me know straight away.

[Central dome]

ED: Yuri, does she know how she ended up in the tunnel?

[Biodome]

ADELAIDE: And keep the comms clear.

[Central dome]

ADELAIDE [OC]: Everything goes through me, got that?

[Sickbay]

MAGGIE: Come on. Just let me out of here. I'm fine. Just groggy.

YURI: You know the rules. Twenty four hours.

[Biodome]

TARAK: Andy? Andy! Andy! There you are. Are you all right?

(Andy has his back to Tarak, and he is soaking wet, pouring onto the floor.)

TARAK: Andy. Andrew. Look at me.

[Sickbay]

(Yuri is watching a man speaking Russian on the monitor.)

MAGGIE: Is that your brother?

YURI: It's only a repeat. The solar flares are still up. Are you okay?

MAGGIE: Yeah. Just, you know.

YURI: He makes me laugh, though. It's his husband. He spends money like an idiot! Last year, for Mikhail's birthday, he said don't buy me anything.

(Behind Yuri, Maggie starts to jerk.)

YURI: Let's save money. Georg says fine, okay. His birthday comes around, turns out Georg has bought him a car. Top of the range. And the thing is, he's used Mikhail's credit stamp. So Mik's saying, that means I bought it myself. Georg says it's the thought that counts.

(Maggie's lips are cracked. She stops jerking.)

MAGGIE: Where does he live?

YURI: Oh, just outside Dagestan.

MAGGIE: Where's that?

YURI On the Caspian Sea. Here you go.

(He pulls up a map.)

MAGGIE: By the sea.

YURI: Well, technically it's more of a lake.

MAGGIE: Earth is so much water.

YURI: Yeah. Just look at her. Forty million miles away.

MAGGIE: It has so much beauty.

(Her voice changes, as if she is many in one.)

MAGGIE: We should like that world.

(Yuri turns around and sees Maggie, water pouring out her mouth.)

YURI: This is Sickbay. We have a situation. Maggie's condition has. I don't know. I don't know what it is. It's water, just pouring out.

ADELAIDE [OC]: Yuri, calm down.

[Biodome]

ADELAIDE: Just tell me what's happened to her.

YURI [OC]: The skin is

[Sickbay]

YURI: Sort of broken around the mouth. And she's exuding

[Biodome]

YURI [OC]: Water, like she's drowning.

ADELAIDE: Tarak, this area's unsafe. We're going back. Tarak? Tarak!

DOCTOR: Where was he?

[Central dome]

ED: Yuri, keep her contained. Seal the door at maximum. I'm on my way!

[Biodome]

(The Doctor and Adelaide see Tarak on his knees with Andy's hand on his head. Water is pouring from both of them.)

DOCTOR: Andy, just leave him alone.

ADELAIDE: Step away from him.

DOCTOR: I can help, I promise. I can help. Just leave that man alone.

ADELAIDE: I order you to stop. Stop, or I'll shoot.

DOCTOR: Andy, I'm asking you to take your hand away from him and listen to me.

(Andy releases Tarak.)

DOCTOR: There now, that's better, hmm? So, you must be Andy. Hello.

(Tarak looks at them. He has been transformed, too.)

DOCTOR: We've got to go.

(The chase is on. Adelaide and the Doctor get to the airlock first.)

DOCTOR: Set the seals on maximum!

(They get into the airlock just before Andy fires a jet of water at them.)

[Sickbay]

ED: What the hell?

[Central dome]

MIA: That's not Maggie. What's happened to her? Yuri, what is she?

STEFFI: Captain, we need you back here.

ADELAIDE [OC]: Just tell me that Maggie is contained.

[Biodome airlock]

ADELAIDE: Can you confirm, Ed?

[Sickbay]

ED: Confirmed. She's locked in.

ADELAIDE [OC]: Keep surveillance till I get back.

[Biodome airlock]

ADELAIDE: And close down all water supplies. All pipes and outlets. Don't consume anything.

[Central dome]

ADELAIDE: Have you got that, everyone? That's an order. Don't drink the water.

[Biodome airlock]

ADELAIDE: Don't even touch it. Not one drop.

DOCTOR: Can you talk? Human beings are sixty percent water, which makes them the perfect host.

ADELAIDE: What for?

DOCTOR: I don't know. I never will. Because I've got to go. Whatever's started here, I can't see it to the end. I can't.

(Andy and Tarak start gushing water at the airlock seals.)

DOCTOR: This thing's airtight, yeah?

ADELAIDE: And therefore watertight.

DOCTOR: It depends how clever the water is.

(Bang.)

ADELAIDE: They're fusing the system.

DOCTOR: Abandon ship!

(They run out into the walkway. Andy and Tarak get through the airlock and chase them.)

[Tunnel 1]

(They get back to where Gadget is standing guard. The Doctor gets out his sonic screwdriver.)

ADELAIDE: Doctor, we haven't got time.

DOCTOR: They can run faster than us. We need a lift.

[Central dome]

(Whatever the Doctor is doing gives Roman a jolt.)

ROMAN: Hey!

[Tunnel 1]

GADGET: Gadget gadget.

DOCTOR: Get on behind me.

ADELAIDE: That thing goes at two miles an hour.

DOCTOR: Not any more. Trust me.

GADGET: Gadget gadget.

DOCTOR: Gadget gadget.

(Flames come out of Gadget's exhaust. Roman shakes like he's being electrocuted. Gadget zooms off leaving burning tyre marks.)

ADELAIDE: The Central Dome airlocks have got Hardinger seals. There's no way they can get in.

DOCTOR: Come on. Come on.

GADGET: Gadget gadget.

DOCTOR: Come on. Come on.

ADELAIDE: I thought you hated robots.

DOCTOR: I do.

(They get Gadget into the airlock just before Andy and Tarak arrive.)

[Airlock]

ADELAIDE: We're safe. It's hermetically sealed. They can't get in.

DOCTOR: Water is patient, Adelaide. Water just waits. It wears down the clifftops, the mountains, the whole of the world. Water always wins. Come on.

[Central dome]

ADELAIDE: Biodome Tunnel is out of bounds. Andy and Tarak are infected.

[Passageway]

ADELAIDE: Repeat, infected. Make no contact. And if they make the slightest move, tell me.

[Central dome]

ADELAIDE [OC]: I'm going to the Medical Dome.

[Tunnel 2]

DOCTOR: Blimey, it's a distance. You could do with bikes in this place.

ADELAIDE: Every pound in weight equals three tons of fuel.

DOCTOR: Yeah, I know. But bikes.

[Sickbay]

ADELAIDE: Has that door got a Hardinger seal?

ED: No, just basic.

ADELAIDE: Then the moment she heads for the door, we evacuate. Got that?

ED: Pulse is low. Electrical activity in the brain seems to be going haywire.

ADELAIDE: Can she talk?

YURI: Don't know. She was talking before we noticed the change, but

ADELAIDE: Maggie, can you hear me? Do you know who I am? Your commanding officer, Captain Adelaide Brooke. Can you tell me what happened?

DOCTOR: Hoorghwall in schtochman ahn warrellinsh och fortabellan iin hoorgwahn.

ED: What language is that?

DOCTOR: Ancient North Martian.

ADELAIDE: Don't be ridiculous.

ED: It's like she recognised it.

DOCTOR: And her eyes are different. They're clear, like she's closer to human.

ED: Not close enough for me.

DOCTOR: Where do you get your water from?

ADELAIDE: The ice field. That's why we chose the crater. We're on top of an underground glacier.

DOCTOR: Tons of water. Marvellous.

YURI: But every single drop is filtered. It's screened. It's safe.

DOCTOR: Looks like it, yeah.

ED: If something was frozen down there. A viral life form held in the ice for all those years.

DOCTOR: Look at her mouth. All blackened, like there's some sort of fission. This thing, whatever it is, doesn't just hide in water, it creates water. Tell me what you want.

YURI: She was looking at the screen. At Earth. She wanted Earth. A world full of water.

ED: Captain, With me.

(Adelaide and Ed turn their backs on Maggie and walk away.)

ED: I'm sorry, but it's an unknown infection and it's spreading. That demands Action Procedure One.

ADELAIDE: Do you think I don't know that?

ED: I think you need reminding.

ADELAIDE: Yeah.

ED: Well, at least I'm good for something.

ADELAIDE: Now and again.

ED: That's almost a compliment. Things must be serious.

DOCTOR: Sorry, sorry, but, Action One, that means evacuation, yeah?

ADELAIDE: We're going home. This is Captain Brooke. I'm declaring Action One. Repeat to all crewmembers, this is Action One with immediate effect. Evacuate the base.

[Central dome]

STEFFI: I'll store the central computer. Mia, strip the cargo down to essentials. Roman, on your feet.

ROMAN: But we came all this way.

GADGET: Gadget gadget.

STEFFI: And you can kiss that robot goodbye. It's too heavy. Now shove it in storage and hurry up.

ADELAIDE [OC]: Steffi, what's your estimate on shuttle viability?

STEFFI: It's a nine month flight. It'll take us at least three hours to load up everything we need.

ADELAIDE [OC]: You've got twenty minutes. And give me a report on Andy and Tarak.

STEFFI: Still in the Biodome tunnel. They're just standing there, like they're waiting.

ADELAIDE [OC]: Keep an eye on them.

[Sickbay]

ADELAIDE: And make that twenty minutes fifteen. Ed, line up the shuttle. Go straight to ignition status.

ED: Doing it now.

YURI: But what about Maggie?

ADELAIDE: She stays behind. We've got no way to contain her on board. Close this place down. I want the power directed to the shuttle.

DOCTOR: Of course, the only problem is

ADELAIDE: Thank you, Doctor. Your spacesuit will be returned. And good luck to you.

DOCTOR: The problem is, this thing is clever. It didn't infect the birds or the insects in the biodome, it chose the humans. You were chosen. And I told you, Adelaide, water can wait. Tarak changed straight away, but when Maggie was infected it stayed hidden inside her, no doubt so it could infiltrate the Central Dome. Which means

ADELAIDE: Any one of us could already be infected. We've all been drinking the same water.

DOCTOR: And if you take that back to Earth, one drop. Just one drop.

ADELAIDE: But we're only presuming infection. If we can find out how this thing got through. When it got through. Yuri, continue with Action One. I'm going to inspect the ice field.

DOCTOR: Right. I should leave. Finally, I should leave. Yuri, me old mate, no point in me seeing the ice field. No point at all. No. Adelaide!

[Tunnel 3]

(The Doctor catches up with Adelaide.)

DOCTOR: All I'm saying is, bikes. Little foldaway bikes. Don't weigh a thing.

[Sickbay]

(Yuri wheels his trolley of medical supplies to the door.)

YURI: I'm sorry.

(He goes out, turning off the power and sealing the door. Maggie goes to short out the isolation room door.)

[Central dome]

ROMAN: Even if she gets past the Medical Dome, she'll never get past the Hardinger seal at this end, right?

ED: So we keep saying. Camera's down. We've lost her.

(Maggie gets out of the isolation chamber and calls out. Andy and Tarak hear her, and walk back down Tunnel 1.)

[Water extraction module]

DOCTOR: They tell legends of Mars from long ago, of a fine and noble race who built an empire out of snow. The Ice Warriors.

ADELAIDE: I haven't got time for stories.

DOCTOR: Perhaps they found something down there. Used their might and their wisdom to freeze it.

ADELAIDE: Doctor, we need to find any sort of change in the water process. We've got to date the infection.

COMPUTER: Access denied.

ADELAIDE: You don't look like a coward, but all you've wanted to do is leave. You know so much about us.

DOCTOR: Well, you're famous.

ADELAIDE: It's like you know more.

DOCTOR: This moment, this precise moment in time, it's like. I mean, it's only a theory, what do I know, but I think certain moments in time are fixed. Tiny, precious moments. Everything else is in flux, anything can happen, but those certain moments, they have to stand. This base on Mars with you, Adelaide Brooke, this is one vital moment. What happens here must always happen.

ADELAIDE: Which is what?

DOCTOR: I don't know. I think something wonderful happens. Something that started fifty years ago, isn't that right?

ADELAIDE: I've never told anyone that.

DOCTOR: You told your daughter. And maybe one day she tells the story to her daughter. The day the Earth was stolen and moved across the universe. And you

ADELAIDE: I saw the Daleks. We looked up. The sky had changed. Everyone was running and screaming. And my father took hold of me.

[Memory - attic]

BROOKE: Stay here. Don't move. I've got to go out. I'm going to find your mother, but I'm coming back. I promise you. I'm coming back.

ADELAIDE [OC]: I never saw him again.

[Water extraction module]

ADELAIDE: Nor my mother. They were never found. But out on the streets, there was panic and burning. I went to the window, and there, in the sky, I saw it, Doctor. And it saw me. It stared at me. It looked right into me. And then it simply went away. I knew, that night, I knew I would follow it.

DOCTOR: But not for revenge.

ADELAIDE: What would be the point of that?

DOCTOR: That's what makes you remarkable. And that's how you create history.

ADELAIDE: What do you mean?

DOCTOR: Imagine it, Adelaide, if you began a journey that takes the human race all the way out to the stars. It begins with you, and then your granddaughter, you inspire her, so that in thirty years Susie Fontana Brooke is the pilot of the first lightspeed ship to Proxima Centauri. And then everywhere, with her children, and her children's children forging the way. To the Dragon Star, the Celestial Belt of the Winter Queen, the Map of the Watersnake Wormholes. One day a Brooke will even fall in love with a Tandonian prince, that's the start of a whole new species. But everything starts with you, Adelaide. From fifty years ago to right here, today. Imagine.

ADELAIDE: Who are you? Why are you telling me this? Doctor, why tell me?

DOCTOR: As consolation.

(The maintenance log pops up on screen.)

ADELAIDE: Andy Stone. He logged on yesterday.

ANDY [on screen]: Maintenance log, twenty one twenty, November 2059. Number three water filter's bust. And guess what? The spares they sent don't fit. What a surprise. Over and out.

DOCTOR: A filter! One tiny little filter and then the Flood.

ADELAIDE: But that means the infection arrived today, and the water's only cycled out of the biodome after a week. The rest of us can't be infected. We can leave. Ed, we're clean.

[Central dome]

ADELAIDE [OC]: How are we doing?

ED: Shuttle's active. Stage one. I haven't got time to convey the protein packs. If you want food you're going to have to carry it by hand. Start loading, right now.

[Tunnel 3]

ADELAIDE: You were right, Doctor.

DOCTOR: What about?

ADELAIDE: Bikes!

[Central dome]

(Adelaide gives the Doctor his spacesuit.)

ADELAIDE: Now get to your ship. I'm saving my people, you save yourself. I know what this moment is. It's the moment we escape. Now get out.

ED: Everyone, stay focused.

MIA: I'll swap them round. Roman, what about you?

ROMAN: Protein packs thirty to thirty six.

ED: Hurry up, Roman.

(Andy and Tarak have climbed onto the roof of Tunnel One and are walking to the dome, but no one notices the schematic showing this. In the hubbub, an alarm sounds.)

ADELAIDE: Ditch the central containers. We don't need them.

STEFFI: Units forty one, forty two and forty three.

YURI: Unit forty one is here.

ADELAIDE: Roman, try to condense the oxygen membranes. We can lose ten pounds. Faster, come on! Ed, how's the fuel jets?

ED: Cooling down in about thirty seconds.

STEFFI: Captain, we've got all the hard drives.

(Andy and Tarak lie face down on the dome.)

ADELAIDE: What the hell's that noise? Mia, you lot, shut up.

ED: It's the module sensors. Exterior twelve. The cameras are down, but there's pressure on top of the module. Two signals right above us.

STEFFI: That means they're on the roof?

YURI: How did they get inside the Dome?

ED: They used the maintenance shafts.

MIA: The shaft's open and they haven't got spacesuits.

ED: They breathe water.

STEFFI: But they'd freeze.

YURI: They've got that internal fission.

MIA: But we're safe, they can't get through, can they? Can they?

(The roof creaks.)

ROMAN: This place is airtight.

STEFFI: Can it get through? Ed, can it get through?

ED: I don't know! Water itself isn't motile, but it has some sort of persistence.

ADELAIDE: Everyone, listen to me. That's ten feet of steel-combination up there. We need all the protein packs or we're going to starve. Now keep working. Roman, watch the ceiling. Ed, get to the shuttle. Fire it up.

ED: I can carry more than this lot, Captain.

ADELAIDE: That's an order!

ED: Captain.

(And the Doctor continues to stand there, holding his spacesuit, and remembering how history recorded the end of Bowie Base One. Finally he turns and leaves.)

[Airlock]

COMPUTER: Access denied. Access denied.

ADELAIDE [OC]: Tell me what happens.

DOCTOR: I don't know.

ADELAIDE [OC]: Yes, you do.

[Central dome]

ADELAIDE: Now tell me.

DOCTOR [OC]: You should be with the others.

ADELAIDE: Tell me! I could ramp up the pressure in that airlock and crush you.

DOCTOR [on monitor]: Except you won't. You could have shot Andy Stone, but you didn't.

[Airlock]

DOCTOR: I loved you for that. Imagine, imagine you knew something. Imagine you found yourself somewhere. I don't know, Pompeii.

[Central dome]

DOCTOR [OC]: Imagine you were in Pompeii.

ADELAIDE: What the hell's that got to do with it?

DOCTOR [OC]: And you tried to save them.

[Airlock]

DOCTOR: But in doing so, you make it happen. Anything I do just makes it happen.

[Central dome]

STEFFI: Captain, we need you right now.

[Airlock]

ADELAIDE [OC]: I'm still here.

[Central dome]

DOCTOR [on monitor]: You're taking Action One. There are four more standard action procedures. And Action Five is?

ADELAIDE: Detonation.

DOCTOR [on monitor]: The final option. The nuclear device at the heart of the Central Dome. Today, on the twenty first of November 2059, Captain Brooke activates that device, taking the base and all her crew members with her. No one ever knows why. But you were saving Earth. That's what inspires your granddaughter. She takes your people out into the galaxy because you die on Mars. You die today. She flies out there like she's trying to meet you.

ADELAIDE: I won't die. I will not.

DOCTOR [on monitor]: But your death creates the future.

ADELAIDE: Help me. Why won't you help, Doctor? If you know all of this, why can't you change it?

DOCTOR [on monitor]: I can't.

ADELAIDE: Why can't you find a way? You could tell me, I don't know

DOCTOR [on monitor]: I'm sorry, but I can't. Sometimes I can, sometimes I do. Most times I can save someone, or anyone. But not you. You wondered all your life why that Dalek spared you. I think it knew. Your death is fixed in time for ever. And that's right.

ADELAIDE: You'll die here too.

DOCTOR [on monitor]: No.

ADELAIDE: What's going to save you?

DOCTOR [on monitor]: Captain Adelaide Brooke.

(Adelaide releases the airlock.)

ADELAIDE: Damn you.

(Water pours through the storage area ceiling.)

ROMAN: Water! We've got water!

MIA: Captain! Get back! Get back! Captain! Don't touch it, Roman. Get back. Get back.

ADELAIDE: Everyone, we're abandoning this section. Get to the shuttle. Yuri, lead the way. Section B corridor, now.

MIA: Get that, and that.

ADELAIDE: Close it!

(Yuri closes the storage area door where the water is pouring in.)

MIA: Yuri, did that water touch you?

YURI: I'm safe

STEFFI: Did it touch you?

[Airlock]

STEFFI [OC]: Yuri, did that water touch you?

YURI [OC]: I'm clean. I'm dry.

ADELAIDE [OC]: Everyone

[Central dome]

ADELAIDE: Section B is out.

MIA: But we can get

ADELAIDE: Listen to me.

[Airlock]

ADELAIDE [OC]: Take every pack that you can. We'll go round. We'll make our way out through Section F.

STEFFI [OC]: Transferring oxygenation to Section F. Mia you take the redline stock. And hurry up!

(The dome ceiling cracks, and Steffi gets trapped behind a curtain of water.)

YURI: Steffi, come!

[Airlock]

MIA [OC]: Steffi, get back!

ADELAIDE [OC]: Steffi, keep back.

YURI [OC]: Get back!

MIA [OC]: Steffi!

YURI [OC]: Get back, Steffi!

[Central dome]

(Steffi backs into the communications alcove.)

ADELAIDE: Screen!

YURI: Shut the door! Close the door!

ROMAN: Steffi, we'll come get you, okay? We'll come get you!

ADELAIDE: Steffi!

STEFFI: Captain!

ADELAIDE: We'll open the access panel.

[Airlock]

ADELAIDE [OC]: We'll get you out through the back.

[Central dome]

ADELAIDE: Get out of here. Move it!

STEFFI: Captain, it's inside!

[Airlock]

ADELAIDE [OC]: Steffi!

MIA [OC]: Steffi, get back!

ADELAIDE [OC]: We're coming, Steffi. Hold on!

[Tunnel 0]

(The Doctor leaves the airlock.)

ROMAN [OC]: The access panel's fused, Captain. We can't open it.

YURI [OC]: We can't get through!

STEFFI [OC]: I can't move!

[Central dome]

(Steffi is pressed up against the bank of monitors. She presses a play button and a message plays from a little girl.)

ULRIKA [on monitor]: Hallo, Mutti. Hallo, Mars! Sag hallo. (continues in German.)

(Water pours onto Steffi.

(The Doctor walks slowly back, listening to the little girl's message.)

ADELAIDE: Steffi! Can you hear me?

MIA: Oh, my God.

ADELAIDE: Out. Get out.

(Mia leaves. Steffi has been transformed. She leaves the communications alcove.)

[Corridor]

ADELAIDE: Ed, we're going round the long way. How are we doing?

[Shuttle]

ED: All systems online one hundred percent. Not a single delay. Don't you worry, Captain, we are going to fly.

(The shuttle's engines fire up.)

[Outside the Base]

(The Doctor is walking outside, silhouetted against the shuttle exhaust.)

ADELAIDE [OC]: I need air in section F right now. All of you

YURI [OC]: Locking chamber three. Locking chamber four.

ROMAN [OC]: The water is going to get through.

ADELAIDE [OC]: Keep moving!

YURI [OC]: Gate five is open. Gate six is open.

[Section F]

YURI [OC} Quickly, come on.

(Roman looks up at the ceiling.)

MIA: I've got twenty five to thirty locked down.

(A drop of water falls on Roman's face.)

ADELAIDE: Roman, come on. With me.

ROMAN: You'd better go.

[Outside the base]

ADELAIDE: Don't just stand there. Move.

ROMAN [OC]: You'd really better go without me.

[Section F]

ROMAN: I'm sorry, Captain. One drop.

(Roman starts jerking.)

MIA: Roman! Roman!

YURI: Leave him, come on.

[Outside the base]

MIA [OC]: We can't just leave him.

YURI [OC]: Come on.

MIA [OC]: Let me go!

YURI [OC]: We've got to go.

MIA [OC]: Roman!

[Section F]

YURI: I'm so sorry.

(Maggie enters the shuttle and aims a jet of water at Ed. He closes the bulkhead, but not in time.)

ED [OC]: Captain. The shuttle is down.

ADELAIDE: What the hell do you mean?

[Outside the base]

ED [OC]: Compromised. It was Maggie.

ADELAIDE: Get out of there.

ED [OC]: Too late.

[Shuttle]

(Ed activates the autodestruct.)

ED: They want this ship to get to Earth. Got no choice.

[Outside the base]

ED: Hated it, Adelaide.

[Shuttle]

ED: This bloody job. Argh.

[Outside the base]

ED [OC]: You never gave me a chance.

[Section F]

ED [OC]: You never could forgive me.

[Shuttle]

(Ed's eyes have changed.)

ED: See you later.

(He hits the destruct button and the shuttle goes KaBOOM. The blast knocks the Doctor off his feet and wreaks havoc in Section F.)

[Section F]

YURI: We're losing oxygen!

[Outside the base]

YURI [OC]: The hull is broken!

DOCTOR [memory]: I'm not just a Time Lord, I'm the Last of the Time Lords. They'll never come back. Not now. I've got a Tardis. Same old life, last of the Time Lords. And they died and took it all with them. The walls of reality closed, the worlds were sealed, gone for ever. The Time Lords kept their eye on everything. It's gone now. But they died, the Time Lords! All of them, they died. I'm the last of the Time Lords.

(The Doctor returns to Bowie Base One.)

[Section F]

DOCTOR: Mia, take this sealant, fix that leak. Yuri, open emergency oxygen. Adelaide, don't just sit there. That's better. The Dome's still got integrity! It's ten feet of steel-combination, made in Liverpool. Magnificent workmanship.

ADELAIDE: It can't be stopped. Don't die with us.

DOCTOR: No, because someone told me just recently. They said I was going to die. They said he will knock four times, and I think I know what that means, and it doesn't mean right here, right now, because I don't hear anyone knocking, do you?

(Andy thumps three times on the bulkhead door.)

DOCTOR: Three knocks is all you're getting.

(He electrifies the bulkhead.)

DOCTOR: Water and electricity, bad mix. Now then, what else have we got?

ADELAIDE: But there's no way to fight them.

DOCTOR: Heat! They use water, so we can use heat. Works against the Ice Warriors, works against the Flood. Ramp up the environment controls and steam them.

ADELAIDE: But you said we die. For the future, for the human race.

DOCTOR: Yes, because there are laws. There are Laws of Time. Once upon a time there were people in charge of those laws, but they died. They all died. Do you know who that leaves? Me! It's taken me all these years to realise the Laws of Time are mine, and they will obey me!

(Bang! Sparks! Alarms!)

ADELAIDE: Environment controls are down. Sorry, Doctor, it looks like history's got other ideas.

DOCTOR: I'm not beaten yet. I'll go outside, find the heat regulator.

(His spacesuit helmet is damaged.)

DOCTOR: Not beaten. Not beaten! You've got spacesuits in the next section.

(But water is pouring through the ceiling.)

DOCTOR: We're not just fighting the Flood, we're fighting time itself. And I'm going to win!

(Maggie is in the Water Extraction module. She emits a high pitched noise and the glacier starts to crack.)

YURI: Something is happening to the glacier.

DOCTOR: Think-a think-a think-a think. What have we got? Not enough oxygen. Protein packs, useless. Glacier, glacier mints, minty, Monty, molto bene, bunny, bonny, bish bash bosh. Argh. The room, the room, look at the room. Section F. What's in Section F? Anyone!

YURI: Nothing. It's just storage.

DOCTOR: Storing what?

YURI: I don't know. Er, the weather spikes, the robots, the atom clamps.

DOCTOR: Atom clamps. Atom clamps? Who needs atom clamps? I love a funny robot.

(The Doctor opens a unit to reveal -)

GADGET: Gadget gadget.

(The Doctor gives Gadget something to hold.)

DOCTOR: You take that. Good boy.

GADGET: Gadget gadget.

(The Doctor puts on the auto-remote gloves.)

DOCTOR: Off we go then.

GADGET: Gadget gadget.

(Adelaide presses a button on a computer keyboard. The monitor lights up with Warning.)

DOCTOR: Come on, come on!

(The Doctor steers Gadget through fire and water.)

COMPUTER: Implementing Captain's protocol.

DOCTOR: Adelaide? What are you doing?

MIA: Oh, my God. Action Five.

DOCTOR: If I have to fight you as well, then I will.

COMPUTER: Nuclear device now active and primed.

(The countdown has started at 100.)

COMPUTER: Nuclear device now active and primed.

DOCTOR: Blast off!

GADGET: Gadget gadget.

(Gadget zooms forward.)

DOCTOR: Faster!

(Gadget streaks across the sands of Mars. All the infected people add their voice to the sonics that are making the crack bigger. Gadget reaches the Tardis.)

COMPUTER: Nuclear device entering final process.

[Outside the Tardis]

GADGET: Gadget gadget.

(Gadget raises the key to the lock.)

[Section F]

DOCTOR: And we're in! Ha, ha.

(The countdown reaches 43.)

[Tardis]

(The Doctor sets the Tardis controls remotely via Gadget.)

GADGET: Gadget gadget.

[Section F]

(23, 22 and the wind of a materialising Tardis fills the area. 8, 7, 6, 5, 4, 3, 2, 1. Bowie Base One goes KaBOOM!)

[Street]

(The Tardis materialises on a snow covered Georgian street. The Doctor leads Adelaide, Mia, Yuri and Gadget out.)

DOCTOR: Isn't anyone going to thank me?

(Gadget shuts down.)

DOCTOR: He's lost his signal. Doesn't know where he is.

ADELAIDE: That's my house.

DOCTOR: Don't you get it? This is the twenty first of November 2059. It's the same day on Earth. And it's snowing. I love snow.

MIA: What is that thing? It's bigger. I mean, it's bigger on the inside. Who the hell are you?

(Mia runs away.)

ADELAIDE: Look after her.

YURI: Yes, ma'am.

(Yuri runs after Mia.)

ADELAIDE: You saved us.

DOCTOR: Just think though. Your daughter, and your daughter's daughter, you can see them again. Family reunion.

ADELAIDE: But I'm supposed to be dead.

DOCTOR: Not any more.

ADELAIDE: But Susie, my granddaughter. The person she's supposed to become might never exist now.

DOCTOR: Nah! Captain Adelaide can inspire her face to face. Different details, but the story's the same.

ADELAIDE: You can't know that. And if my family changes, the whole of history could change. The future of the human race. No-one should have that much power.

DOCTOR: Tough.

ADELAIDE: You should have left us there.

DOCTOR: Adelaide, I've done this sort of thing before. In small ways, saved some little people, but never someone as important as you. Oh, I'm good.

ADELAIDE: Little people? What, like Mia and Yuri? Who decides they're so unimportant? You?

DOCTOR: For a long time now, I thought I was just a survivor, but I'm not. I'm the winner. That's who I am. The Time Lord Victorious.

ADELAIDE: And there's no one to stop you.

DOCTOR: No.

ADELAIDE: This is wrong, Doctor. I don't care who you are. The Time Lord Victorious is wrong.

DOCTOR: That's for me to decide. Now, you'd better get home. Oh, it's all locked up. You've been away. Still, that's easy.

(He points his sonic screwdriver at the front door, and it opens.)

DOCTOR: All yours.

ADELAIDE: Is there nothing you can't do?

DOCTOR: Not any more.

(Adelaide goes inside, drawing her gun and closing the door. Then we hear the shot and see the energy blast light up the window. The Doctor turns around and in his head, he watches the history record change her place of death from Mars to Earth. Susie Fontana Brooke still goes into space, though.)

ADELAIDE [OC]: I don't care who you are. The Time Lord Victorious is wrong.

(The Doctor turns to see an Ood looking at him.)

DOCTOR: I've gone too far. Is this it? My death? Is it time?

(The Doctor falls to his knees. The Ood vanishes. He gets up again and goes inside the Tardis.)

[Tardis]

(The Cloister bell tolls.)

DOCTOR: No.