[Control room]

(Sarah Jane falls to the floor. Clyde rushes to her.)
CLYDE: No! Sarah Jane.
KAAGH: She lives. She is my prize to take back to Sontar once Earth is destroyed. There, she will pay for the Doctor's crimes.
CLYDE: We'll stop you. You might be a Sontaran, but you're only one.
KAAGH: One Sontaran is all it takes. Secure her with the other female.
(Professor Skinner obeys.)

[Outside the Observatory]

MARIA: Luke, we really have to do something.

[Control room]

(Kaagh seizes Clyde.)
KAAGH: Your species' biology is primitive. Laboratory analysis at my ship could provide valuable information for the High Command.
(Maria opens a grill from the inside.)
MARIA: Clyde! Over here!
(Clyde gets free and runs to the opening.)
CLYDE: See you, Spud.
(The children escape into the underground bunker complex.)
KAAGH: Argh. I will fry your blood, half-form.

[Corridor]

CLYDE: Boy, that guy has a big case of little man complex.
(Kaagh shoots at them just as they turn a corner. They come to a junction.)
MARIA: Which way?
LUKE: This way.
(Kaagh gets to the junction and sniffs for their scent.)
CLYDE: I can't see.
LUKE: Just keep running.
MARIA: Faster. He'll catch us.
CLYDE: How far does this bunker go?
LUKE: Miles.
CLYDE: In forty five minutes this place could come in really handy.
(Kaagh's shot hits the hand rail, and they run again, ending up some stairs at a door.)
LUKE: I think I took a wrong turn. Sorry.
CLYDE: It's stuck.
MARIA: Clyde, we have to get it open.
CLYDE: First time in my life I wish I carried a lipstick.
(By the time Kaagh gets there, the door is closing again.)

[Outside the bunker door]

(Luke grabs a cut tree trunk.)
LUKE: Help me with this.
(They use it to wedge the door shut. Kaagh hammers on the other side.)
CLYDE: I reckon that is a toad in the hole.
MARIA: Come on.

[Laboratory]

(Sarah Jane wakes up in an armchair. Lots of bits of equipment on a bench, and a water cooler.)
SARAH JANE: Where's Clyde?
LUCY: I don't know. Dad locked you in. What's happened to him? He's acting like some sort of robot.
SARAH JANE: He's being controlled by an alien, a Sontaran. And if we don't get out of here, it's going to destroy the world. My bag! Oh, my sonic lipstick.
LUCY: Your what?
SARAH JANE: If only Luke were here. We'll just have to manage on our own, won't we?

[Bannerman Road]

CHRISSIE: You and Maria moving to America, I just can't get my head around it.
ALAN: If I take the job. Looks like someone's doing all right, anyway. Changed your car?
CHRISSIE: Oh, it's Ivan's. I just borrowed it. Don't change the subject. I mean it, Alan, it would be weird not having you here. We get on much better as friends than we did as husband and wife. I'll miss you.
ALAN: If I go.
CHRISSIE: Of course you'll go. You live for work. You always did.
ALAN: It's what you never understood, Chrissie. I live for Maria. I lived for Maria and you. That's all work was ever about. Looking after the two of you. That's why whatever I do, it has to be right for Maria.
(Alan's phone rings.)

[Woods / Bannerman Road]

MARIA: Dad? You have to help us.
ALAN: Maria, slow down. What's happened?
MARIA: We're at the Tycho Radio Telescope, near a village called Goblin's Copse. Sarah Jane's been captured by a Sontaran. We've got about forty minutes before it destroys Earth. You have to help us talk to Mister Smith.

[Laboratory]

LUCY: A jamming device.
SARAH JANE: Something that will interfere with the radio telescope.
LUCY: And we're going to build it?
SARAH JANE: What's wrong? Haven't you inherited any scientific aptitude from your father?
LUCY: Yeah. But if we jam the telescope won't they be able to trace the source?
SARAH JANE: Exactly.

[Bannerman Road]

CHRISSIE: Where are you going, Alan? Not Mary Jane's?
ALAN: I have to do something for Maria. Maybe you should get Ivan's car back before he finds out you've borrowed it.
CHRISSIE: What about Maria?
ALAN: Maria's fine. She's just er, she left her library book with Sarah Jane. It has to go back today, that's all.
CHRISSIE: All right. We've got to talk this American thing through properly, like a family.
ALAN: Yeah, of course.
(Chrissie drives away. Alan gets the spare key from behind a shrub and lets himself into number 13. Chrissie reverses back to check on him.)

[Attic]

ALAN: Mister Smith? Mister Smith, I need you.
MR SMITH: Oh, Mister Jackson. This is a surprise.
ALAN: It's that sort of a day.

[Woods]

(Maria's phone rings.)
MARIA: Dad?

[Outside Sarah Jane's home]

(Chrissie finds an unlocked window and climbs in.)
CHRISSIE: Some people never learn.

[Attic / Woods]

MR SMITH: Sontarans are a clone species originating from the planet Sontar. They are fearless, well trained, strategically intellectual, and immensely strong.
LUKE: But they can be beaten? They must have a weakness.
(Chrissie is listening to the conversation.)
MR SMITH: Sontarans do not eat food. They intake pure energy by means of a probic vent at the base of their skull. This point is their sole weakness.
CHRISSIE: What on Earth is going on?
ALAN: Chrissie?
MARIA: Mum? What are you doing there?
CHRISSIE: I think I get first dibs on the questions. Alan, what's going on?
ALAN: Maria, I'm going to have to call you back.

[Woods]

CLYDE: Sarah Jane's going to be so happy.
LUKE: That's not what's important. All that matters is saving Mum.
MARIA: I think I've got an idea about that. Come on.

[Outside Sarah Jane's home]

(Alan hustles Chrissie outside.)
CHRISSIE: A role-playing game?
ALAN: It's an internet thing, only some of it's in the real world. You know, looking for clues, solving puzzles.
CHRISSIE: Like a treasure hunt, like when we were dating? All afternoon spent running round back lanes and plodding across fields looking for a golden rabbit?
ALAN: That's right.
CHRISSIE: I don't believe you, Alan. I know when you're lying. I've always known. Maria's in danger, isn't she? And it's got something to do with Calamity Jane.
ALAN: Sarah Jane. She fights aliens. Maria helps her.
CHRISSIE: Aliens?
ALAN: They exist, Chrissie. I've seen them. What do you think nearly brought the moon crashing down?
CHRISSIE: Aliens? From space?
ALAN: Believe me.
CHRISSIE: I do. Your mouth didn't twitch.
ALAN: What?
CHRISSIE: The corner of your mouth. It always twitched when you told a fib. It didn't move at all. Come on. We've got to help our daughter.
(They drive off in Ivan's car.)

[Woods]

CLYDE: Whoa. This is your great idea? The Sontaran's space ship?
MARIA: Kaagh said he had a laboratory. If Luke can synthesise a knock-out gas, we can use it on him.
CLYDE: Brilliant.
(Maria puts her hand into the three fingered door control, and it opens.)

[Control room]

SKINNER: The programme is enabled, Commander. The dish will align on schedule and the up-link will begin.
KAAGH: Good. In twenty five minutes, the Tenth Fleet shall be avenged. My name shall be purged of shame. I shall return to Sontar as Kaagh the Avenger.

[Sontaran ship]

CLYDE: We don't know what any of these chemicals are. They're alien.
LUKE: Dylixium chloride, Korazic acid, Lyzirium phosphate. Chemistry lessons with Mister Smith are much more fun than at school.
(An alarm sounds.)
MARIA: What's that?
LUKE: I think we tripped an alarm system.

[Control room]

KAAGH: Intruders on my ship. Ha! The half-forms. Like bugs in a battle-trench bunk, it is time to crush them.

[Sontaran ship]

MARIA: Kaagh will be coming. Luke, you have to get a move on.
LUKE: I can't rush this.
(Clyde leaves.)
MARIA: Where are you going?
CLYDE: If I can spot Kaagh coming, I can buy you more time.
MARIA: Be careful.
CLYDE: See you back at the telescope.

[Laboratory]

(Sarah Jane connects the power to her gizmo.)
LUCY: It's working.
SARAH JANE: And now, we wait.
(One of Skinner's computer screens reports Signal Interference. He types in the command Trace Interference Source.)

[Sontaran ship]

(As Luke works in the small spaceship, Maria looks through the photographs on her phone. Then it comes up Low Battery.)
MARIA: You know, Luke, I don't think I'll ever meet anyone like you again.
LUKE: You won't need to. You've got me.
MARIA: My dad's got a job in America.
LUKE: Are you going with him?
MARIA: I don't know.
LUKE: You can't go, Maria. I don't want you to go.
MARIA: But Luke, it's my dad.
LUKE: But you've always been here.
MARIA: I know, and I'm going to miss you so much. And Sarah Jane, and Clyde. But none of that matters if we don't stop Kaagh. Please, Luke, you have to make this gas.
(Meanwhile - )
CLYDE: Hey, Bilbo. Over here.
(Clyde throws a stick then runs. Kaagh fires and misses.)
KAAGH: By Sontar, I will crush you with my bare hands, bite-size.
(Back at the Observatory, Skinner enters the living area and sees the gizmo. Sarah Jane and Lucy are hiding behind the door. They make their escape, locking him in.)

[Outside the Observatory]

CLYDE: Someone! Anyone! Let me in!
(Sarah Jane opens the door.)
SARAH JANE: Clyde.
CLYDE: Quick.
(They lock Kaagh out.)

[Sontaran ship]

LUKE: Yes! I've got it.

[Control room]

CLYDE: Luke's working on this knock-out gas. Reckons he can take Kaagh out with it.
(The timer says 20:29.)
SARAH JANE: I'm not sure we've got time.
LUCY: I've watched my dad working. I can try and stop the program.
(She sits at the keyboard and starts typing.)
LUCY: The system's encrypted. I can't get into it.
SARAH JANE: Can we sabotage the dish? The antenna has to be aligned to transmit Kaagh's programme to the satellite. If it can't operate, he might as well howl at the moon.
LUCY: There's an operating system.
CLYDE: Where is it?
LUCY: Round the other side of the complex.
(Sarah Jane retrieves her bag, and lipstick.)
SARAH JANE: You stay here. See if you can break the code.

[Laboratory]

(Kaagh punches the door down.)
KAAGH: You miserable organism, you let them escape.

[Road]

(Chrissie stops by Sarah Jane's car.)
CHRISSIE: I thought you said they were at a telescope.
ALAN: Yeah, well, obviously the telescope must be near.
(He tries ringing Maria.)
MARIA [OC]: This is Maria. Try me again later.
ALAN: Oh, she's still not answering, then. Maybe the battery's dead.
CHRISSIE: Well, where do we go now, Alan? Maria's in danger, and I hope I don't have to remind you whose fault that is.

[Outside the Observatory]

MARIA: Are you sure this gas is going to work?
LUKE: I don't have any Sontaran physiological data, but the anaesthetic would disable a human for two hours.
MARIA: And a Sontaran?
LUKE: We only need a few minutes.
(They spot two lights in the air.)
MARIA: It's the Sontaran's drones. Run!

[Woods]

(But they cannot outrun them.)
SARAH JANE: Get down!
(Clyde tackles Maria and Luke, knocking them both down, as Sarah Jane sonicks the drones.)
LUKE: Mum!
SARAH JANE: Quickly. Maria, you have to go with Clyde. He's going to try to disable the dish. Luke, you're with me. We have to try everything we can.

[Telescope control]

MARIA: This is what drives the dish?
CLYDE: Lucy says there's a central control system transponder. All we've got to do is take it out.
MARIA: Doesn't that sound a bit too easy?
CLYDE: The hard part's finding it.

[Control room]

SARAH JANE: Any luck with the programme?
LUCY: It's no good. I can't do this.
LUKE: Let me.
LUCY: What? I mean, no disrespect or anything, but you're just a kid and we're looking at the end of the world here.
SARAH JANE: No disrespect, Lucy, but you really aren't much more than a kid, either, and can you see the flaw in Einstein's Theory of Relativity? Luke can. And he can save the world. He's had practice. Fifteen minutes to go. Why isn't Kaagh here to see his plan succeed?

[Telescope control]

CLYDE: It's got to be around here somewhere.
MARIA: Fourteen minutes, Clyde.
(Skinner grabs Clyde.)
MARIA: Let him go!
CLYDE: Go, Maria. Find the transponder. Now!
(Maria runs.)
CLYDE: Get off me. Get off!
(Maria spots a red switch box and opens it.)
KAAGH: Is this what you are looking for, female half-form? Remember the first law of battle. Think like your enemy. The second law of battle. Anticipate them.
(Kaagh puts the transponder back into its slot in the Transponder Fuse Unit and shuts the box.)
KAAGH: The operating system remains fully functional.
(The telescope dish moves into position.)

[Woods]

(Chrissie is tottering along in high heels.)
CHRISSIE: Alan. Alan! This is impossible.
ALAN: Just leave them there.
CHRISSIE: Are you mad? These are designer shoes. You want some squirrel moving into the most des res in the forest?

[Control room]

SARAH JANE: Luke, you've only got four minutes.
LUKE: The code is a bi-axial algorithm. It's not Earth mathematics. I'm having to try progressive cross-referencing number bases.
SARAH JANE: You have to hurry.
(He remembers Maria opening Kaagh's spaceship.)
LUKE: Six! That's it, six. Sontarans have three fingers on each hand.
LUCY: What?
LUKE: We use the decimal system. We have ten fingers. That's it. I've cracked the code. I've disabled the program.
KAAGH: Move away from the controls.
(Kaagh and Skinner bring in Maria and Clyde.)
MARIA: I'm sorry. We didn't do it. The antenna's still operational.
KAAGH: These half-forms might be primitive, but I admire their spirit. I shall remember them honourably on my return to Sontar. Earth will be a worthy sacrifice to the Empire.
SARAH JANE: No, Kaagh. Luke broke the program code. He disabled it. You can't take control of the satellites.
KAAGH: The third law of battle. Always have a Plan B. Activating my sleeper agent.
(Lucy gasps and grabs at the back of her neck.)
CLYDE: She was one of them all along? And I fancied her.
KAAGH: She was unaware of my control. Another rule of war. Infiltrate deep within your enemy, then infiltrate deeper still.
SARAH JANE: Lucy, no.
KAAGH: You might give your life, but will you sacrifice this half form?
MARIA: Do it.
SARAH JANE: I can't.
MARIA: It's me or it's Earth.
(Sarah Jane throws her sonic lipstick onto the desk.)
SARAH JANE: One life is as sacred as an entire planet.
(Lucy reinitialises the programme from her phone.)
KAAGH: When the program reloads, it will automatically transmit to the satellites and target your nuclear installations around the world. Sontar-ha.
SARAH JANE: This isn't conquest. It's annihilation. The Earth will be useless to your Empire.
KAAGH: I will have wiped the Sontaran defeat from history. My name will live for all eternities to come. My people will scream it as a battle-cry.
CLYDE: Now I have to admit, that is kind of cool.
MARIA: You're killing innocent people.
SARAH JANE: Stop the program. This isn't battle, it's murder.
KAAGH: Your planet defied Sontar. That can never be. We will have victory over all. Nothing will stop us.
CHRISSIE: Try my size fives, Humpty.
(And sticks one of her metal stiletto heels into his probic vent. The energy release knocks Kaagh out and throws Chrissie backwards.)
MARIA: Mum! Mum.
(Sarah Jane retrieves her lipstick and zaps Skinner and Lucy.)
SARAH JANE: Consider yourselves de-activated.
(Luke disconnects Lucy's phone just as the download reaches 98%.)
MARIA: Mum?
(Luke disconnects Lucy's phone just as the download reaches 98%.)
ALAN: She's all right.
SARAH JANE: What I would like to know is how Chrissie knew where to hit a Sontaran. I suppose it can wait.
ALAN: She's coming round.
MARIA: Quickly, the knock-out gas. Give it to me.
LUKE: What for?
MARIA: If we can get Mum home before she comes round, maybe we can convince her that none of this ever happened. She banged her head. Had a bad dream. Anything.
SARAH JANE: Your mum will have saved the world. She won't have a clue.
ALAN: Believe me, it's better this way. We'd never hear the end of it.
CHRISSIE: Maria.
MARIA: Go back to sleep, Mum.
(And gives her a puff of the knock-out gas. Lucy wakes up.)
LUCY: Dad? Dad, are you all right?
SKINNER: What happened? Those lights in the sky. What on Earth is that?
SARAH JANE: Don't worry, Professor. Commander Kaagh has been de-commissioned.
CLYDE: Sontar-ha!

[Sontaran ship]

SARAH JANE: Don't try anything. Your craft's weapons have been disabled, so don't think about coming back.
KAAGH: Defeated by a female and half-forms. I will go, Sarah Jane Smith, but I will not forget you. Sontarans will yet cry my name in battle.
(Kaagh goes into his spaceship and powers it up.)
SARAH JANE: Well, I think that went as well as could be expected, don't you? Now perhaps we should all run.
(They hide behind trees as the ship takes off.)
MARIA: Do you think that's the last we've seen of him?
SARAH JANE: I hope so. Of course, with some people, it really doesn't matter how far they travel. They never really go away.

[Jackson home]

(Chrissie wakes up lying on the floor.)
MARIA: Mum? Mum, are you okay?
CHRISSIE: What happened?
ALAN: I always said these heels will be the death of you. You tripped, banged your head.
MARIA: I was really worried, Mum.
CHRISSIE: Oh, it's all right, love. I had such a weird dream, though. I dreamed your dad got a job in America.
ALAN: I did. That is, if I take it.
MARIA: I'd love to go to America. You can still visit, can't you?
CHRISSIE: You try and stop me. They've got shops the size of aircraft hangars there.
ALAN: Are you sure? I mean, think about everything you'd be leaving behind.
MARIA: Dad, you can't ever leave the universe behind.

[Attic]

(Six weeks later.)
MR SMITH: I have completed a further scan, Sarah Jane. I have detected no Sontaran energy signatures.
SARAH JANE: Maybe Kaagh isn't coming back after all. Thank you, Mister Smith.
MARIA: Sarah Jane?
SARAH JANE: So, everything packed?
MARIA: I just wanted to come and take one last look. And I wanted to say goodbye to Mister Smith.
MR SMITH: In atomic terms, we all remain connected by the universe, Maria, so I will say au revoir.
SARAH JANE: I really don't know what your father did to him.
MARIA: Will you come and see us? Please?
SARAH JANE: Of course I will. And Maria, I really am sorry for how I reacted when you told me about America.
MARIA: It doesn't matter. We were sort of busy.
SARAH JANE: No, I was wrong. You see, well, for the first time, I felt I'd found a family. And so soon, so suddenly, it felt like I was losing it. Losing the daughter I always wanted.

[Bannerman Road]

(The Jackson house has already been sold.)
CLYDE: Bye.
LUKE: Bye.
MARIA: Safe landings.
CHRISSIE: Bye.
ALAN: Come on, come on.
(Maria and Alan get into the taxi. Chrissie stands next to Sarah Jane.)
CHRISSIE: I remember it all, you know.
SARAH JANE: Sorry?
CHRISSIE: The Sontaran. What really happened with my shoe. Don't worry, I won't say anything. They deserve a new start. We all do.
SARAH JANE: Thank you.
(The taxi drives away.)

[Attic]

(Night time.)
LUKE: I'll miss her.
CLYDE: Yeah, me, too.
SARAH JANE: I learned a long time ago that if you're missing somebody, just look up at the night sky. Whoever it is, wherever they are, chances are they're looking at the stars just like you. Sometimes, for all its size, the universe isn't such a big place after all.