(We are flown over a large underwater base with lots of lights on.)
MORAN [OC]: Private journal of Captain Jonathan Moran, 21st November 2119. We have located a craft of unknown origin on the lake floor. Visual scans in situ revealed nothing, so we have brought the craft on board and myself and the crew will now investigate.

[Main hangar]

(The mystery craft is a cross between Thunderbird Four and a Star Trek space shuttle - there are steps on the back hatch which has lowered as a ramp up into a singe empty compartment with one large rectangular object inside. Moran is a large man standing just inside it.)
MORAN: How did they miss this in the initial survey?
LUNN: Cass says it was buried, and then the currents of the water must have shifted the rubble around.
(Cass is a deaf lady who uses sign language, and Lunn is her interpreter. Another man wearing glasses - Bennett - is scanning with a Geiger counter.)
PRITCHARD: A conversation needs to be had about who owns this spaceship.
MORAN: Can we stop calling it a spaceship? We don't know what it is.
PRITCHARD: A case could be made that this is an asset, and my company has bought the rights to all assets 
MORAN: Whoa, whoa. What's this? Lunn, grab me a torch, will you?
(There are four strange symbols apparently scratched into the port side of the inner hull.)
MORAN: It was found on MOD property, even if that property is underwater.
(Lunn goes to a wall cabinet and we see something flash past at speed. When he shuts the cabinet door a face is briefly seen behind his own, but as he turns around there is no one there.)
MORAN: What you bought is the oil under the ground. Lunn! Where's the torch?
(O'Donnell, a young lady with pony tail and baseball cap, gets the torch from Lunn and hands it to Moran. He shines it on the symbols and we see them in his eyes. The two of them leave the vessel.)
CASS via LUNN: Can I go in?
MORAN: What is the radiation count?
BENNETT: Pretty much background level.
O'DONNELL: Anything more, it would have shown up on the initial survey twenty years ago.
LUNN: (signs to Cass) If it's not safe, how come you can go in?
CASS via LUNN: How long do you think it's been down here?
BENNETT: Well, there's next to no corrosion. I've not seen technology like this 
MORAN: Please don't say on Earth.
BENNETT: On Earth before.
(O'Donnell laughs.)
MORAN: (sighs) Maybe it's some kind of experimental craft that got left behind when they abandoned the site.
BENNETT: Wait, you think the Army would just lose a prototype weapon?
MORAN: You're new to the military, aren't you, son?
LUNN: Cass says he might be right. It might have been here since the 1980s, when the valley flooded.
(Pritchard is peering at a circular dot design on the forward bulkhead of the craft, when he sees a hand reach for him. It belongs to a strange figure in Victorian style clothes and top hat, with long white sideburns. Then the craft's engines ignite, spurting flame.)
MORAN: Cass!
(Moran pushes Cass to safety and gets incinerated himself. Alarms sound and everyone flees.) 
LUNN: Come on! Move! Come on, we need to go now!
COMPUTER: Fire in the main hangar. Safety protocols have been initiated. All crew must evacuate immediately. This safety message was brought to you by Vector Petroleum.

[Corridor]

(Sealing a doorway.)
O'DONNELL: We can't just leave him in there!
PRITCHARD: There was something in the spaceship, I saw it!
BENNETT: O'Donnell. O'Donnell, he's dead. Didn't you see?
LUNN: The fire, are we safe out here?
BENNETT: It's fine. The CO2 will put the fire out.
O'DONNELL: (to Pritchard) It was you! You were messing about with the controls on that ship!
(Cass looks past them all and screams, and grabs Lunn to protect her. Moran is standing behind them, lips moving. There are black holes where his eyes should be.)
BENNETT: Moran. But, we just saw you 
O'DONNELL: He's. Oh, my God. He's a  ghost.
(Moran is joined by the other figure, and they both reach out for the crew.)

[Corridor]

(Three days later, the Tardis materialises. We are shown an overturned chair and a base that seems to be empty. The Doctor talks to the Tardis.)
DOCTOR: What's wrong? You're not happy. Why aren't you happy? Tell me.
CLARA [OC]: Come on! we're on a roll!
(She stands in the Tardis doorway.)
CLARA: Monsters, things blowing up. Oh, hey, can we go back to that place where the people with the long necks have been celebrating New Year for two centuries? I left my sunglasses there. And most of my dignity.
DOCTOR: Why have you brought us here?
CLARA: Here being?
(She shuts the Tardis door.)
DOCTOR: Underwater. Some sort of a base. The technology's twenty second century. Maybe military, maybe scientific.
CLARA: Is there a crew?
DOCTOR: Must be, somewhere, if there's oxygen.
(They walk down the corridor.)
CLARA: I want another adventure. Come on, you feel the same. You're itching to save a planet, I know it.
(He smiles behind her back.)

[Mess hall]

(A big mural of a dragon or serpent threatening some men in a small wooden sailing boat. Their garments look suspiciously like ST:TNG style, including the colours. This is where the overturned chair is, along with a lot of mess.)
CLARA: Doctor, look at this.
DOCTOR; Well. Looks like you got your wish.
CLARA: Food fight?
(A knife is stuck in a wall. Clara twangs it.)
DOCTOR: I think there was more to it than that. Whatever it was, it happened pretty recently.
(He sticks his finger into a cup of originally hot liquid.)
DOCTOR: Seven or eight hours ago. No bodies, though.
CLARA: And they took provisions. Okay, so something or someone forced the crew to abandon the base. Maybe they went for a swim in the creepy flooded village outside.
(They look through the windows.)
CLARA: Oh, yeah. You see, this is more like it.
(She holds out her hand for a high five?)
CLARA: Oh, come on. Don't leave me hanging.
(The Doctor walks out of the room. She follows after a few moments.)

[Corridor]

(Yet another one, but they all look the same.)
DOCTOR: Look. Told you. Crew.
(Moran and the ghost are squatting on the floor with their backs towards the Doctor and Clara.)
DOCTOR: Hello, sailors!
(The figures stand and turn, their lips moving.)
DOCTOR: Right, I did not expect that. Hands up who expected that.
(The figures walk forward.)
DOCTOR: Wait, wait. I don't think they're going to hurt us. I think that they're just curious.
(The alien stands nose to nose with the Doctor, while Moran looks down at Clara.)
CLARA: Are you sure?
DOCTOR: Well, I mean, define sure. Look at you lovely chaps. What's happened to you, then?
(The figures turn away, still muttering to themselves.)
DOCTOR: Come on.
(The Doctor and Clara follow the figures.)
CLARA: What are they?
DOCTOR: I haven't a clue. Isn't that exciting? 

[Main hangar]

(The doors open. The Doctor and Clara enter, and the doors close behind them. The fire has long been extinguished.)
CLARA: Where did they go? What is it, some kind of submarine?
DOCTOR: No, it's alien.
(They go inside the spaceship. The Doctor runs his hand over the rectangular object and sees the symbols on the wall. We see them in his eye. He points to them, and Clara picks up the light and shines it on the markings.)
DOCTOR: That's weird. The Tardis hasn't translated it.
(A strange, hissing sort of sound. Clara turns.)
CLARA: (sotto) Hey, look, they're back.
DOCTOR: Hello! Did you want to show us this? It's very nice.
CLARA: Wait, are they saying something?  
(Moran takes a fire axe from the wall, but it is very heavy for him.)
CLARA: Okay, they now appear to be arming themselves.
DOCTOR: Yes, I spotted that, too.
(They leave the craft as the other ghost takes a harpoon gun.)
DOCTOR: Was it something she said? She does that. She once had an argument with Gandhi!
(Moran swings the axe, and just misses.)
CLARA: I'm starting to see why the crew did a runner.
(The harpoon gun is fired and dodged. The Doctor and Clara run out. The ghosts walk through a wall, but their weapons have to be left behind.)

[Corridor]

(A hand reaches through the wall next to Clara. She cries out. Moran emerges, making them back away down the corridor, then the other rises up through the floor behind them. Clara grabs at the Doctor's arm.)
CLARA: Run!
(A door at the end of the corridor is opened.)
O'DONNELL: In here! Quick! 

[Faraday cage]

(The ghosts peer in though the round window in the door, but do not enter. The Doctor returns their stare.)
DOCTOR: What are you?
(The ghosts leave.)
PRITCHARD: Who the hell are you, and what are you doing here?
DOCTOR: This is Clara, and I'm the Doctor.
(He shows them his psychic paper.)
PRITCHARD: You're from UNIT.
DOCTOR: Well, if that's what it says.
PRITCHARD: I'm Pritchard, this is Bennett.
O'DONNELL: O'Donnell! Are you really the Doctor? I'm a huge fan! I mean, er, you know  Nice work.
LUNN: Tim Lunn, I sign for Cass.
DOCTOR: Tell me, what about those things out there? What are they? Why are they trying to kill us?
BENNETT: Well, they're er, they're ghosts.
DOCTOR: They're not ghosts.
LUNN: Cass is saying 
DOCTOR: Thank you, but I actually don't need your help. I can speak sign. (signs) Go ahead.
(Cass signs her reply.)
DOCTOR: No, no, actually, I can't. It's been deleted for semaphore. Someone get me a selection of flags.
CASS via LUNN: One of the ghosts is our previous commanding officer. The other, um moley guy, we don't know what he is.
DOCTOR: He's from the planet Tivoli.
BENNETT: See? I told you he was an alien. Didn't I say that?
DOCTOR: Weird thing is, they're not violent. They're too cowardly. They wouldn't say boo to a goose. They're more likely to give the goose their car keys and bank details. When did they first appear?
O'DONNELL: Oh, did you see that spaceship in the hangar? Yeah, we found that on the lake bed and we'd just got it on board and one of the engines started up and then Moran got (pause)
Moran was killed.
CASS via LUNN: Then they appeared and pretty much straight away started trying to kill us. So we grabbed what we could and we were looking for somewhere to hide, and that's when we realised the ghosts couldn't come in here.
CLARA: What is this place?
DOCTOR: It's a Faraday cage. Completely impenetrable to radio waves, and apparently, whatever those things are out there. So, who's in charge now? I need to know who to ignore.
CASS via LUNN: That would be me.
LUNN: Her.
PRITCHARD: Actually, that would be me.
(Richard Pritchard, Vice President of Sub-aquatic Resources, hand the Doctor his card.)
PRITCHARD: I represent Vector Petroleum. We've obtained the mining rights to the oil.
DOCTOR: The oil? Where are we?
(The Doctor tosses the card on the floor, and Pritchard picks it up again.)
BENNETT: This used to be a military training site. There was a dam overlooking it, but the dam burst and the valley was submerged.
PRITCHARD: Then twenty years ago, we discovered a massive oil reservoir underneath it.
COMPUTER: Good morning. Entering day mode.
(The lights brighten.)
O'DONNELL: Okay, it's morning. We can go outside now.
LUNN: Thank God for that.
PRITCHARD: At last, we can get out of here.
CLARA: Morning?
BENNETT: (Taking a towel from a hook.) Yeah, we're too far below the surface for daylight, so we have to demarcate artificial days and nights.
(O'Donnell opens the door.)
DOCTOR: I'd like to have a further look at that spaceship, but what about those things that aren't ghosts?
O'DONNELL: Oh, it's all right. They only come out at night.
CLARA: (sotto) Weird how that is not comforting. 

[Main hangar]

DOCTOR: If whatever they are 
PRITCHARD: They're ghosts.
DOCTOR: They're not ghosts. Have been trying to kill you, why haven't you abandoned the base?
PRITCHARD: That was my call. We've got about a trillion dollars worth of mining equipment here. We're not just going to abandon it  What? If it all goes pear-shaped, it's not them that lose a bonus.
DOCTOR: It's okay. I understand. You're an idiot. Come to mention it, why is there a Faraday cage on the base?
BENNETT: It's the mining equipment. It runs on nuclear fission. The Faraday cage has been lined with lead to act as a shelter in the event of a radiation leak.
DOCTOR: So, we are fighting an unknown homicidal force that has taken the form of your commanding officer and a cowardly alien, underwater, in a nuclear reactor. Anything else I should know? Someone got a peanut allergy, or something?
(The Doctor and Clara go back into the spaceship.)
DOCTOR: It all started with this ship. This is where the answer will be.
(He looks down at a section of the deck, then removes a hatch.)
DOCTOR: What's happened to the stuff you've removed? This is for long-haul flights. There should be a suspended-animation chamber for the pilot right here. Plus, one of the power cells is missing.
PRITCHARD: Power cell?
(He runs up the steps into the spaceship.)
DOCTOR: Yeah. You can see the casing is empty.
(Cass and Lunn are having a vigorous discussion.)
LUNN: It's not safe out here!
CLARA: What's the matter?
LUNN: She won't let me look inside the spaceship. She says it's not safe. I'm saying it's not safe out here.
PRITCHARD: I imagine they're pretty valuable.
DOCTOR: What?
PRITCHARD: I mean powerful. Those power cells. I imagine they're pretty powerful.
DOCTOR: Well, they can zap a vessel from one side of the galaxy to the other, so, you know, take a wild stab in the dark.
PRITCHARD: And the missing one must still be out there.
DOCTOR: Yes, well, otherwise. Sorry, why is this man still talking to me?
O'DONNELL: We haven't removed anything. There hasn't been time.
(Pritchard leaves, then the Doctor leaves the spaceship.)
DOCTOR: So what have we got? Moran dies, and then those things appear. They can walk through walls. They only come out at night and they're sort of see-through.
CLARA: Doctor, wait, you're not saying  

[Bridge]

(Computer stations, control panels on walls, and a nice illuminated map of the base.)
DOCTOR: They're ghosts! Yeah, ghosts 
CLARA: You said there was no such thing. You actually pooh-poohed the ghost theory.
DOCTOR: Yes, well, well, there was no such thing as, as socks or smartphones and badgers until there suddenly were. Besides, what else could they be? They're not holograms, they're not Flesh Avatars, they're not Autons, they're not digital copies bouncing around the Nethersphere. No, these people are literally, actually, dead. Wow. This is, it's amazing! I've never actually met a proper ghost.
CASS via LUNN: Moran was our friend.
CLARA: (sotto) The cards.
DOCTOR: Oh! Oh, right you are.
(He fumbles in his pocket for a set of record cards.)
CLARA: (sotto) Oh, come here.
(Clara sorts through them looking for the right one. I completely understand why it was difficult not to get captured. It was my fault, I should have known you didn't live in Aberdeen. I didn't mean to imply that I don't care. No one is going to get eaten / vapourised / exterminated / upgraded / possessed / mortally wounded turned to jelly we'll all get out of this unharmed. She clears her throat and hands him the next one.)
DOCTOR: Ahem. I'm very sorry for your loss. I'll do all I can to solve the death of your friend slash family member slash pet.
(Clara gives in a Look and takes the card back.)
DOCTOR: But don't you see what this means? Death! It was the one thing that unified every single living creature in the universe, and now it's gone. How can you just sit there? Don't you want to go out there right now, wrestle them to the ground and ask them questions until your throat falls out? What's death like? Does it hurt? Do you still get hungry? Do you miss being alive? Why can you only handle metal objects? Oh, I didn't know I'd noticed that. Okay, so they'll try to kill you, blah, blah, blah. What does that matter? You come back. A bit murder-y, sure, but even so! Calm, Doctor, calm. You were like this when you met Shirley Bassey. Okay. Question one. What is a ghost? Question two. What do they want?
(The lights go out.)
O'DONNELL: Whoa. Whoa, what's happening?
COMPUTER: Good evening. Entering night mode.
O'DONNELL: That's not right. We're switching back into night mode again. This can't happen! No, no, no!
(She sits at a computer terminal. Then a distant bell starts to toll.)
BENNETT: Er, what's doing that?
CLARA: Doctor?
DOCTOR: The Tardis Cloister Bell!
(He runs out.)

[Tardis]

CLARA: Doctor, what's wrong?
DOCTOR: It must be the ghosts. That's why she was upset when we got here.
CLARA: Why? I don't understand.
DOCTOR: It's just what I was saying. You live and you die. That's it. The ghosts are aberrations. A splinter of time in the skin. They're unnatural. She wants to get away from them.
CLARA: So, what do we do?
(The Doctor turns a handle on the console. The Cloister Bell stops and the engines power down.)
DOCTOR: Put the handbrake on.
(Clara takes off her jacket and heads for the doors.)
DOCTOR: Whoa! Ho, ho, ho, ho! Where do you think you're going?
CLARA: Out there, where the action is.
DOCTOR: Look, you, er  
CLARA: What?
DOCTOR: Oh, this is my own fault. I like adventures as much as the next man. If the next man is a man who likes adventures. Even so, don't, don't go native.
CLARA: What do you mean? I'm not.
DOCTOR: Look, there's a whole dimension in here, but there's only room for one me.
CLARA: Wait, wait a second. You just raved about ghosts like a kid who had too much sherbet.
DOCTOR: Do you know what you need? You need a hobby.
CLARA: I really don't.
DOCTOR: Or even better, another relationship. Come on, you lot, you're bananas about relationships. You're always writing songs about them, or going to war, or getting tattooed 
CLARA: Doctor, I'm fine.
DOCTOR: I just felt that I, I, I had to say something.
CLARA: I know. And I appreciated it.
DOCTOR: Because I've got a duty of care.
CLARA: Which you take very seriously, I know.
DOCTOR: So can I stop now?
CLARA: Please. Please do.
(They leave. The Tardis groans.)

[Airlock]

O'DONNELL [OC]: Attention, all crew. The Drum has switched to night mode early so grab provisions and make your way to the Faraday cage.
(A man is in a full dry suit. He removes his helmet whilst talking and puts it down. A figure is on the other side of the airlock door.)
PRITCHARD: That you, Bennett? I went out looking for that missing power cell. Okay, contractually, it's a grey area, but I reckon we can argue everything non-indigenous is an asset and therefore 
(He realises something is not right.)
PRICHARD: Bennett?
(Moran steps forward on the other side of the door.)
PRITCHARD: We're meant to be in day mode! You shouldn't be here.
(Moran whispers incomprehensibly.)
PRITCHARD: What? What? What what are you saying?
(As he looks through the window he sees Moran touch the outer door override control. Pritchard tries to get to his helmet but - )
PRITCHARD: No, Moran! Don't!
(The airlock is suddenly flooded.)

[Mess hall]

(Clara is helping Bennett gather provisions.)
O'DONNELL [OC]: Pritchard, you are unaccounted for. Contact the bridge or get to the Faraday cage immediately. Pritchard, contact the bridge or get to the Faraday cage!
BENNETT: I'd love to work for UNIT, Earth's first line of defence, and all. I'm probably not suited, though. Not much of a fighter. More of a bleeder.
(A figure in a dry suit has his back to them.)
CLARA: Pritchard! Where you have you been? Everyone's been looking for you. What's with the wet suit?
BENNETT: Yeah, where have you been? 

[Bridge]

BENNETT [OC]: O'Donnell, it's okay. Pritchard's in here!.
O'DONNELL: Pritchard, you moron. Grab your stuff, we're locking down early. In case I can't get this back into day mode.

[Mess hall]

CLARA: Is he all right?
(Something bumps against the windows. It is a figure in a dry suit floating outside.)
BENNETT: Man overboard. Man overboard! We need a rescue team in the water now!
CLARA: Bennett, wait! It's Pritchard.
(The figure with them turns around to show its black eye sockets. Cass, Lunn and the Doctor run in.)
CLARA: He's a ghost. He's another ghost.
(Ghost Pritchard picks up a chair and advances towards them.)

[Bridge]

(O'Donnell works at the computer consoles.)
O'DONNELL: Come on, come on. Come on, come on, come on, come on, come on.
(In the mess hall, the lights come on, Pritchard vanishes and the chair falls to the floor.)
COMPUTER: Good morning. Entering day mode.
(They watch CCTV of what happened to Pritchard on a wall screen. The alien ghost is a few steps behind Moran.)
PRITCHARD [on screen]: No! No, Moran! Don't!
DOCTOR: They're working out how to use the base against us. Altering the time settings so they can go about uninhibited, opening the airlocks. They're learning.
CLARA: And now there's three of them.
BENNETT: Cass, what do we do?
CASS via LUNN: We abandon the base. Topside can send down a whole team of marines or ghost-busters or whatever.
DOCTOR: Wait, wait.
CASS via LUNN: I can't force you to leave, so you can stay and do the whole cabin in the woods thing and get killed or drowned, if you want. But my first priority is to protect my crew.
CLARA: (sotto) But we're coming back, aren't we?
DOCTOR: (sotto) Yes, we're coming back.
CASS via LUNN: O'Donnell, contact Topside. Tell them we're abandoning the base on my orders.
(O'Donnell uses a sort of field telephone.)
O'DONNELL: Topside, Topside, this is Lance Corporal Alice O'Donnell from Drum Control. Over.
TOPSIDE [OC]: Drum Control, this is Topside. We have received your message. Submarine on its way. Over.
O'DONNELL: Repeat, Topside. Over.
TOPSIDE [OC]: We've received your request for a rescue sub. It's two minutes away. Over.
O'DONNELL: Topside, who did you speak to and when was this request made? Over.
TOPSIDE [OC]: Drum Control, it was in Morse code and arrived maybe half an hour ago. Said it was urgent, comms were down, two crew members critically ill, full paramedic team requested. Over.
(The Doctor snatches the handset.)
DOCTOR: Topside, this is the Doctor, UNIT security visa seven one zero Apple zero zero. You may be familiar with my work. Call back the sub.
TOPSIDE [OC]:'Doctor, why would
DOCTOR: Call it back! We have a hazardous and undefined contagion on board. This base is now under quarantine.
(He puts the handset down.)
BENNETT: What did you do that for?
DOCTOR: Well, none of us sent the message, did we? So that means that the ghosts sent it, which means they want that crew down here.
LUNN: Why would they do that?
DOCTOR: Well, I don't know, but I'm pretty certain it's not so they can all form a boy band. Okay. We solve this on our own. The ghosts can only come out at night so they change the base's time settings. Why? What's different at night?
O'DONNELL: It's mainly atmospheric. The lights are dim, the noise from the engines is muffled.
DOCTOR: No. Something, something else.
CASS via LUNN: The diagnostic sweep. When the systems are checked, that stops at night to save power.
DOCTOR: What systems specifically?
O'DONNELL: Life support, the locks. They're electromagnetic. They have to be secured in case of flooding, so throughout the day, they're checked, one by one, every few seconds.
DOCTOR: The answer is in there somewhere, I can smell it.
CLARA: Doctor, what do we do?
DOCTOR: O'Donnell. Excellent work, returning the base to day mode.
O'DONNELL: Shut up. It was nothing  You really think so?
DOCTOR: Now put it back into night mode.
O'DONNELL: What!
DOCTOR: We know nothing. We don't know what they want. That's what's getting us killed. Well, I won't run. Not any more. So, O'Donnell, kindly put the base back into night mode. We want to know what these ghosts are after? We ask them. We're going to do the impossible. We're going to capture a ghost. 

[Mess hall]

(The lights go down in sequence in the modular corridors, then the night lights come on. Pritchard is half inside a wall, the alien is standing sideways halfway up a wall and Moran is hanging down from the ceiling.)
COMPUTER: Good evening. Entering night mode.
(Bennett enters nervously.)
BENNETT: H-Hey, how's it going?
(Ghost Pritchard steps fully out of the wall in front of him and he runs out.)

[Bridge]

(Everyone is on CCTV on various wall screens.)
O'DONNELL: Bennett's got them moving, and Clara's in position.
(The Doctor is at the big wall map of the base.)
DOCTOR: Clara, Bennett is going to run across the top of the T-junction to your right

[Corridor]

DOCTOR [OC]: In about ten seconds. Draw the ghosts towards you. Turn right, and then take second left.
(The running man passes the junction, then the alien ghost comes into view, walking just a few yards behind.)
CLARA: Hey! Hey, ghosts. Down here!
(All three follow Clara.)

[Bridge]

DOCTOR: Lunn, they're coming your way. Clara's going to duck down to her left. You've got to keep the ghosts going on the same route they're on now.

[Corridor]

DOCTOR [OC]: Then, after about fifty yards on your left, there is a flood door.

[Bridge]

DOCTOR: O'Donnell will close the door once you're through.

[Corridor]

LUNN: I, I can hear them.

[Bridge]

DOCTOR: Lunn, don't let them see where you go.

[Intersection]

(Lunn steps out, Clara sees him and ducks out to her left just before the ghosts arrive.)
LUNN: Hey! Yeah, this way.
(But the alien and Moran turn to follow Clara. Only Pritchard follows Lunn.)
LUNN: We've got a problem!

[Bridge]

O'DONNELL: They've separated.
DOCTOR: What?
O'DONNELL: Moran and the mole guy are going after Clara.

[Corridor]

O'DONNELL [OC]: Clara, look out. Two ghosts are still on your case. Right behind you.
CLARA: I'm beginning to think we should have let the ghosts in on the plan.

[Bridge]

DOCTOR: Clara, there's a flood door at the end of the corridor, around the corner to your right. We'll close it from here. Listen to me. You've got to get through that door before Moran and the other ghost sees you.

[Flood door]

CLARA: Doctor.

[Bridge]

DOCTOR: Now, O'Donnell, fast as you can!
(Door 17018 closes and Clara stands against it, out of sight of the ghosts, who pass by.)

[Corridor]

LUNN: Guys, I'm nearly at my door.
(Lunn goes through the open doorway.)

[Bridge]

DOCTOR: Now, Lunn, quickly.
(O'Donnell closes the door.)

[Flood door]

LUNN: It saw me. Oh, God.

[Bridge]

LUNN [OC]: It saw me. It's coming through. It's coming through the door.
(They watch as ghost Pritchard steps through the door.)
O'DONNELL: We don't have a camera in there.
(The Doctor stops Cass from leaving.)
DOCTOR: No, no, Lunn. Lunn, can you hear me? Can you hear me? Lunn, what's happening?
(In the flood compartment or whatever it is, Lunn backs up to the rear wall then closes his eyes and cringes as Pritchard comes right up to him and reaches for a wrench on the wall. It stares at the whimpering man, then the wrench falls to the floor with a clatter. They see Pritchard walking off down a corridor.)
DOCTOR: Lunn, can you hear me? Lunn? Lunn?

[Floor door]

DOCTOR [OC]: Can you hear me? Lunn, Lunn? Lunn, Lunn! What's happening? Lunn? Lunn? Can you hear me?
LUNN: I'm okay.

[Bridge]

O'DONNELL: Cass, he's alive.
LUNN [OC]: It didn't hurt me. I'm okay
DOCTOR: What? What's wrong with you? Why didn't it hurt you? Bennett, you're on again. Bennett, where are you?
(O'Donnell calls him up on CCTV.)
O'DONNELL: There. Oh, God, look.
DOCTOR: Bennett, can you hear me?

[Corridor]

DOCTOR [OC]: There are two ghosts just around the corner from you.
BENNETT: (sotto) Yes, thanks, I'd noticed.
(The alien and Moran are swaying and muttering at each other.)

[Bridge]

DOCTOR: The Faraday cage is across the intersection and down the corridor to your right. This last bit is down to you.
(Bennett runs, the ghosts follow. Pritchard joins them.)

[Corridor]

BENNETT: Okay, so, the good news is, they aren't split up any more. Cue Clara!
(Clara appears in the open door to the Faraday cage. The ghosts walk in, and straight through her. She flickers. The door shuts and locks.)

[Outside the Faraday cage]

(The Doctor puts on his sonic sunglasses.)
DOCTOR: We need to talk. Sorry, chaps. Just a hologram. You play a little bit too rough.
(Holo-Clara disappears.)

[Bridge]

(Bennett, Clara and Lunn return. Cass hugs Lunn, and O'Donnell punches Bennett's arm.)
CLARA: I'm fine, by the way, in case any of you were worried.

[Outside the Faraday cage]

DOCTOR: Cass, are you seeing this?

[Bridge]

O'DONNELL: Sonic glasses Wi-Fi locked in. On screen B2.
LUNN: She says she can't see them properly.

[Outside the Faraday cage]

LUNN [OC]: The glass is too thick and they're too far away.
DOCTOR: Open the door. 

[Bridge]

O'DONNELL: What?
CLARA: Doctor, you can't go in there, they will kill you!

[Faraday cage]

DOCTOR: They don't have any weapons or access to any of the controls. They can't hurt me, so open the door.
(Clara gives O'Donnell the nod and the door unlocks. The Doctor steps inside and closes it behind him. Moran steps forward, lips moving, and reaches into the Doctor's body. It is not a comfortable feeling.)
DOCTOR: Cold, isn't it? Take away your weapons and you're not so scary, are you? Is that better, Cass? 

[Bridge]

(Cass looks intently at the faces of the three ghosts on the monitors, who are now enunciating their words clearly and in unison.)
LUNN: She says they're saying the same thing, the same phrase, over and over. They're saying the dark. The score. No, the sword. The for sale? No, the forsaken. The temple.

[Faraday cage]

DOCTOR: What?
LUNN [OC]: Yes, she's sure. The dark, the sword, the forsaken, the temple.
(Now we know what we are looking for, reading the lips it seems obvious.)
LUNN [OC]: Just that. Over and over.
DOCTOR: Dark, sword, forsaken, temple. What does that mean? What are you telling me, big man? Bennett! I need maps. I think I just worked out what our friend here is telling us.

[Bridge]

DOCTOR: They're coordinates.
BENNETT: How can they be coordinates?
DOCTOR: The dark? Space. So, whoever's following the coordinates knows they're going to another planet. The sword?
(The Doctor hands out an apple to Bennett, a knobby ball to O'Donnell, a table tennis ball to Clara and a Vector Petroleum place mat also to Clara in her right hand, and makes them hold them up in a diagonal line.)
DOCTOR: Orion's sword. The sword, the three stars, although one isn't actually a star but the Orion Nebula, hanging down from Orion's belt. But if viewed from back here, the Earth becomes the fourth bit of the sword. So, narrowed it down to a planet now. Getting closer.
(He retrieves the objects and puts them on the map table.)
DOCTOR: The forsaken. The forsaken or abandoned or empty town. See, it's a location, beaming out to someone or something across the universe, over and over. And every time they kill one of us 
CLARA: It strengthens the signal. Another ghost, another transmitter.
O'DONNELL: Which is why they sent for that rescue sub.
DOCTOR: Get more people down here, kill them, make even more ghosts to beam out the coordinates.
CASS via LUNN: But why are they beaming out the coordinates? Is it a distress call?
DOCTOR: It could be. Or a warning. Might even be a call to arms. It could mean, come here, they're vulnerable, help yourself. Wait a minute, though. Wait a minuet. Do you know what this means? It means that they're not a natural phenomenon. It means that someone is deliberately getting people killed, hijacking their souls and turning them into transmitters.
O'DONNELL: But what do the coordinates lead to, though? To us? To the ghosts? What?
DOCTOR: Ah! What the coordinates are for. That is part of the answer to the other question you're all thinking. (blank stares) Really? Come on. None of you? Surely just being around me makes you cleverer by osmosis? What is the other question?
CASS via LUNN: The temple. The fourth part of the directions. What's the temple?
DOCTOR: Finally. It's like pulling teeth. This is the flooded military town. Shops, houses, town square, and this.
CLARA: A church?
(A long narrow building with an annex projecting off at right angles at one end, according to the old aerial photograph.)
DOCTOR: Whatever the coordinates are for, it's in that church. Find that and you're a hop, skip and a jump to stopping them.
BENNETT: Wait, you're not suggesting that? But we're safe now. The ghosts are in the cage. We can get out of here.
DOCTOR: No one has to stay. In fact, I would prefer it if you went. You'll all get in the way and ask ridiculous questions. But, you know, (indicates Cass, Lunn and O'Donnell) you have chosen to protect and serve. (indicates Bennett) You have given yourself to science and the pursuit of knowledge. None of you have chosen anonymous or selfish lives. Go, and a part of you will always wonder, what would have happened if I'd stayed? How could I have helped? What would I have learned? I want you to go. But you should know what it is that you're leaving.
LUNN: Cass says we should go, but everything that happens here is her responsibility now, so she's going to stay. So I, er, guess I should too.
O'DONNELL: Well, count me in. Who wants to live forever, anyway?
BENNETT: Sorry, er, have you gone insane? We can go home.
(O'Donnell does a one shoulder shrug and grins.)
BENNETT: They're ghosts, though. How can they be ghosts? Well, at least if I die, you know I really will come back and haunt you all.
(Later, Bennett is controlling a drone submarine by virtual reality goggles and remote controls on his fingers, left hand for steering, right hand for power.)
BENNETT: Okay, the sub is approaching the town square. Which way is the church?
O'DONNELL North-north-west, one hundred and fifty yards. That's it. Starboard two degrees.
CLARA: What are we looking for, exactly?
DOCTOR: Something that has the power to raise the dead and turn them into transmitters. I expect we'll know it when we see it.
BENNETT: Wait, I've found the church.
DOCTOR: That's it, keep going.
(A large white casket is in amongst the debris in the church ground.)
DOCTOR: Wait. What's that? Move closer. 

[Main hangar]

DOCTOR: It's the suspended-animation chamber from the spaceship.
CLARA: So the pilot could be in there.
DOCTOR: There's something inside there. But it's deadlock sealed. I can't open it. It should be the pilot, it should be. So why do I think it isn't? More questions. Everything I solve, just more questions. I have to go back to the beginning. We arrive, we see the ghosts. They don't kill us. They lead us here, they show us the spaceship. Then they try to kill us.
(He goes inside the spaceship and looks at the symbols on the wall.)
DOCTOR: Not translated by the Tardis. Why?
(He cleans his sunglasses and puts them on to look at the scratched marks. Whirring. Then he takes them off and comes out into the hangar and speaks to Cass.)
DOCTOR: Lunn, translate for me. Whenever I step outside, you are the smartest person in the room. So, tell me, what's weird about this? I know that it's all bonkers but, you know, when you think about it, one thing keeps snagging in your mind. What is it?
CASS via LUNN: The markings on the inside of the spaceship.
DOCTOR: The markings on the inside of the spaceship. Yes! Why?
CASS via LUNN: I don't think they're just words.
DOCTOR: They're not. They're magnets.
BENNETT: Magnets? How?
DOCTOR: Well, a localised and manufactured electromagnetic field, to be precise. The dark. The sword. The forsaken. The temple. When we heard the coordinates for the first time, did anyone expect them not to be that? No, exactly. Me neither. It's like we already knew, somehow. Like the words were already in us.
O'DONNELL: So that writing is the coordinates?
DOCTOR: Everything we see or experience shapes us in some way. But these words actually rewrite the synaptic connections in your brain. They literally change the way you are wired. Clara, why don't I have a radio in the Tardis?
CLARA: You took it apart and used the pieces to make a clockwork squirrel.
DOCTOR: And because whatever song I heard first thing in the morning, I was stuck with. Two weeks of Mysterious Girl by Peter Andre. I was begging for the brush of Death's merciful hand. Don't you see? These words are an earworm. A song you can't stop humming, even after you die.
CLARA: Okay, so, the spaceship lands here. The pilot leaves the writing on the wall so whoever sees it, when they die, they become a beacon of the coordinates, while he slash she slash it snoozes in the suspended-animation chamber 
DOCTOR: Waiting for his slash her slash its mates to pick the message up. My God. Every time I think it couldn't get more extraordinary, it surprises me. It's impossible. I hate it. It's evil. It's astonishing. I want to kiss it to death.
(Alarm sounds.)
COMPUTER: Attention, all crew. Evacuate base immediately. Emergency protocols have been initiated. This safety message was brought to you by Vector Petroleum. Fuel for our futures.
(O'Donnell runs to a wall touch screen. It says Flooding Initiated. Reactor Malfunction. Emergency Cooling.)
O'DONNELL: Oh, no. The ghosts tampering with the day-night settings caused a computer malfunction. Its its first priority is to keep the reactor cool, so it's opening the hull doors and it's flooding the base.
(Water gushes into the corridors.)
LUNN: Cass says, close the internal flood doors. That'll contain the water in the central corridor.
DOCTOR: Where's the Tardis?
O'DONNELL: On the other side.
DOCTOR: We need to get there. It's our only way out.
O'DONNELL: Okay. We've got thirty seconds before the flood doors close.

[Corridor]

CLARA: (to Lunn) Come on!
(O'Donnell and Bennett make it across the central corridor before the flood door closes. Clara, Lunn and Cass are trapped on the other side.)
CLARA: Doctor!
(The Doctor dives under the other closing door just in time. He activates the intercom.)
DOCTOR: I'll get you and the others out. Sit tight, I'll come back for you.
CLARA: Just come over here in the Tardis now.
DOCTOR: The Tardis won't go there. It won't go near the ghosts.
CLARA: You can't just leave us!
DOCTOR: Listen to me. I'm going back in time to when this spaceship landed. If I can understand why this is happening, I can stop them killing anyone else. I can save you. You trust me, don't you, Clara?
(The water fills the central corridor between them. Clara nods her agreement.)
BENNETT: Wait, you're going to go back in time? How do you do that?
DOCTOR: Extremely well. 

[Mess hall]

LUNN: You're sure they're not going to hurt us?
CLARA: They can't get out of the Faraday cage.

[Tardis]

(The Doctor takes off the hand brake and the Tardis dematerialises. Bennett and O'Donnell have acquired coats and scarves from somewhere.)
DOCTOR: Back to before the flood.

[Mess hall]

CASS via LUNN: And you're sure the Doctor won't just leave us here?
CLARA: Guys, look, this is how we roll. He's going to go away, come back and we'll have to listen to how he did it.
(Looking through one of the big windows, they see a figure approaching the Drum through the water from the village.)
LUNN: Is it Moran or Pritchard or the mole guy? How, how did they get out?
CLARA: No, I don't think it's any of them. I think it's a new ghost.
LUNN: What does that mean?
CLARA: It means that something happened in the past, it means that somebody else must have. Oh, no. Oh, no, no, no, no.
(The pale ghostly figure with empty eye sockets is the Doctor.)

To Be Continued...