(The Enterprise is at Red Alert as an alien vessel approaches them.)
SULU: Phaser banks standing by, sir.
CHEKOV: Range forty three thousand and closing.
KIRK: What do you read, Mister Spock?
SPOCK: Configuration unidentified. Ion propulsion, high velocity, though of a unique technology.
KIRK: Any contact, Lieutenant?
UHURA: Hailing on all frequencies, sir. All languages have been attempted. No response. Now using standard interstellar symbols.
KIRK: Keep trying.
UHURA: Aye, sir.
KIRK: Magnification ten, Mister Chekov.
CHEKOV: Aye, sir. Thirty eight thousand and closing.
KIRK: Well, Scotty?
SCOTT: It beats me, but isn't she a beauty?
KIRK: Interesting design.
SCOTT: I've never seen anything like her. And ion propulsion at that. They could teach us a thing or two.
KIRK: Life forms, Mister Spock?
SPOCK: One. Humanoid or similar. Low level of activity. Life-support systems functioning. Interior atmosphere, conventional nitrogen-oxygen. Instruments indicate a transferal beam emanating from the area of the humanoid life form.
KIRK: Directed at what?
SPOCK: Directed at the Bridge of the Enterprise, Captain.
KIRK: Security guard.
UHURA: Security guard to the Bridge.
(A woman materialises and smiles at them.)
KIRK: I'm Captain James Kirk. This is the Starship Enterprise.
(The security guards rush in, she presses a button on her wrist band, the power goes off and everyone collapses. Then the same happens to the crew all over the ship. The woman walks over to Spock, and puts her hand on his head.)
(Later - after the opening titles - the power comes back on and everyone wakes up again.)
SULU: What happened?
KIRK: Helm status, Mister Sulu.
SULU: No change from last reading, sir.
KIRK: Condition reports from all decks, Lieutenant.
UHURA: Aye, sir.
KIRK: Spock. Where's Spock?
MCCOY [OC]: Jim! Jim!
KIRK: Yes, what is it?

[McCoy's office]

MCCOY: You'd better come down to Sickbay

[Bridge]

MCCOY [OC]: Right now.
KIRK: All right. On my way.
UHURA: Deck five. Personnel, no damage.

[Sickbay]

(Spock is lying on a biobed, with a bandage around his head and life-support equipment over his torso.)
MCCOY: Now.
CHAPEL: Functioning.
MCCOY: Thank God.
KIRK: Spock. What happened?
CHAPEL: I found him on the table.
KIRK: Like this?
MCCOY: No, not like this.
KIRK: What happened?
MCCOY: I don't know.
KIRK: You've got him on complete life support. Was he dead?
MCCOY: He was worse than dead.
KIRK: What do you mean?
MCCOY: Jim.
KIRK: Come on, Bones. What's the mystery?
MCCOY: His brain is gone.
KIRK: His what?
MCCOY: It's been removed surgically.
KIRK: How could he survive?
MCCOY: It's the greatest technical job I've ever seen. Every nerve ending in the brain must've been neatly sealed. Nothing ripped, nothing torn, no bleeding. It's a medical miracle.
KIRK: If his brain is missing, then Spock is dying.
MCCOY: No. That incredible Vulcan physique hung on until the life-support cycle took over. His body lives. The autonomic functions continue. But there is no mind.
KIRK: That girl.
SCOTT: Aye.
MCCOY: What girl?
KIRK: From that ship. She took it. I don't know why, or where, but she must have taken it. Bones, how long can you keep him functioning?
MCCOY: I can't give you any guarantee.
KIRK: That's not good enough, Doctor.
MCCOY: If it happened to any of us, I'd say indefinitely. But Vulcan physiology limits what I can do. Spock's body is more dependent on that tremendous brain for life support.
KIRK: Then we'll take him with us.
MCCOY: Take him? Take him where?
KIRK: In search of his brain, Doctor. From what you say, the moment we find it we must restore it to his body, or we lose him.
MCCOY: Jim, where are you going to look? In this whole galaxy, where are you going to look for Spock's brain? How are you going to find it?
KIRK: I'll find it.
MCCOY: Even if you do, I can't restore it. I don't have the medical technique.
KIRK: It was taken out. It can be put back in.
MCCOY: But I don't know how.
KIRK: The thief that took it has the knowledge. I'll force it out of her.
MCCOY: If you don't find it in twenty four hours, you'd better forget the whole thing, Jim.
KIRK: You and Scotty have Spock ready.

[Bridge]

SULU: I've got it again. An ion trail matching when we first saw her.
KIRK: Where does the trail lead to?
CHEKOV: System Sigma Draconis.
KIRK: Lock on, Mister Sulu. Maximum speed.
SULU: Warp six.
KIRK: No question about the trail?
SULU: No mistake, sir.

Captain's log, stardate 5431.4. for fifteen hours and twenty minutes we have been following the ion trail of the spaceship that has Spock's brain. Time left to us, eight hours and forty minutes.

[Bridge]

SULU: Captain, I've lost the trail.
KIRK: All scanners, extreme sweep.
UHURA: Aye, sir.
KIRK: Well?
CHEKOV: Nothing, sir.
UHURA: No signal at all, Captain.
SULU: It's gone, sir. A sudden deaction shift.
KIRK: We've lost her trail, but she went into that system. Mister Chekov, put a schematic of Sigma Draconis on the screen.
CHEKOV: Aye, Captain.
KIRK: Read out, Mister Chekov?
CHEKOV: Sun, spectral type, Gamma nine. Nine planets, three of them, Class M possessing sapient life according to reports and long-range scanning.
KIRK: She was breathing our air. She must've gone to one of them. Show us the three Class-M planets. Mister Chekov.
(Chekov gets up and goes to the viewscreen to point out the relevant items.)
CHEKOV: The one on the left, number three, rates letter B on the industrial scale.
KIRK: Earth equivalent approximately 1485.
CHEKOV: Yes, sir. Second planet Class M, number four, rates letter G.
KIRK: The year 2030.
SULU: But that ship, Captain, either it was many years ahead of us or the most incredible design fluke in history.
KIRK: Third Class M planet, Mister Chekov.
CHEKOV: Number six. No sign of industrial development. At last report, in a Glacial Age. Sapient life plentiful, but on a most primitive level.
KIRK: Now. as I understand it, Mister Chekov, there are three Class-M planets,
CHEKOV: Yes, sir.
KIRK: Not one of which is capable of launching an interstellar flight,
CHEKOV: No, sir.
KIRK: Yet one of them accomplished it.
CHEKOV: Yes, sir.
KIRK: Thank you, Mister Chekov.
UHURA: Captain, I'm picking up high energy generation on planet six.
KIRK: That's the primitive glaciated planet.
CHEKOV: Yes, sir.
KIRK: The source of it?
UHURA: It could be natural. Volcanic activity, steam, any number of causes. But it's very regular.
KIRK: What do your surface readings show, Mister Chekov?
CHEKOV: No sign of organised civilisation. Primitive humanoids picked up at irregular intervals.
KIRK: With regular pulsations of generated energy?
CHEKOV: I can't explain it, sir.
KIRK: I can't afford to guess wrong. I've got to choose the right planet, get there, find the brain. Eight hours and thirty five minutes.
KIRK: Recommendations, Mister Chekov.
CHEKOV: Sigma Draconis Three. It's closest, heaviest population.
SULU: But a technological rating of only three. They couldn't possibly have put that ship we saw into space.
CHEKOV: None of these planets could.
SULU: I say planet four, Captain. At least planet four is ahead of three technologically.
KIRK: But advanced ion propulsion is beyond even our capabilities. It'd be a miracle if they had developed it.
UHURA: What would they want with his brain? What would they want with Mister Spock's brain? What use is it?
KIRK: Yes.
UHURA: Why do they want it?
KIRK: Yes. Why would they want it? Eight hours and thirty four minutes. Planet six is glaciated, you say?
CHEKOV: Several thousand years at least. Only the tropical zone is ice-free.
KIRK: But the energy. Regular. It's there. It's real.
UHURA: Yes, sir. It doesn't make sense, but it's there.
KIRK: Have the transporter room stand by. I'm taking a landing party down to planet six.
UHURA: Aye, aye, sir.
SULU: A hunch, Captain?
KIRK: A hunch, Mister Sulu.
CHEKOV: What if you guess wrong, Captain?
KIRK: If I guess wrong, Mister Spock is dead. Spock will die.

Captain's log, stardate 4351.5. We are beaming down to a primitive glaciated planet in the Sigma Draconis star system. Time left to us to find Spock's brain, eight hours and twenty nine minutes.

[Planet surface]

(Kirk, Scott, Chekov and two security guards beam onto the rocky planet.)
KIRK: Suit temperatures to seventy two. Life-form readings, Mister Spock? (gets a look) Mister Scott?
SCOTT: Scattered. Widely spaced. Humanoid, all right. On the large side.
KIRK: Watch out. We know their development is primitive.
SCOTT: Aye.
KIRK: Read out, Mister Chekov.
CHEKOV: No structures, Captain. No mechanised objects that I can read. No surface consumption or generation of energy. Atmosphere is perfectly all right, of course. Temperature, a high maximum of forty. Livable.
KIRK: You have a thick skin.
SCOTT: Captain! There's someone, something out there in the rocks. Five of them. Humanoid, large.
KIRK: Phasers on stun. I want them conscious.
(The group of bearded, skin clad males with clubs move carefully towards the Starfleet party.)
KIRK: Fire only on my signal. Flank out.
(The primitives suddenly leap up from behind rocks, throwing stones and their clubs. Kirk fires, and stuns the leader. The rest run away.)
KIRK: We mean you no harm. We're not your enemies, we're your friends. We only wish to talk to you.
MORG: You are not the Others?
KIRK: No. We come from a far place. We are men.
MORG: Men?
KIRK: Like yourselves.
MORG: You are small, like the Others.
KIRK: Who are the Others?
MORG: Givers of pain and delight.
KIRK: Do they live here with you?
MORG: No. They come. They give pain and delight.
KIRK: Do they come from the sky?
MORG: They are here. You will see. The Others will come for you. They come for all like us.
KIRK: Do they come for your women as well?
MORG: Women?
KIRK: The female of your kind.
MORG: Your words say nothing.
KIRK: Don't you have a mate?
MORG: Mate?
SCOTT: A companion.
KIRK: Will you take us where we can find the Others?
MORG: (afraid) No one wants to find them.
KIRK: We do. We want to find them. Take us there and we'll let you go.
CHEKOV: Captain, five hundred metres in that direction there's a foundation under the surface. A huge one. Registrations all over the place.
KIRK: Buildings?
CHEKOV: Yes, sir. Immensely old, completely buried. But they were here once.
KIRK: Somewhere down there is where the Others live. Scotty, see if you can find a way down.
SCOTT: Aye, sir.
MORG: No! No! No, do not go there! No! No!
KIRK: It's all right.
(He struggles briefly with the Morg, who escapes and runs off.)
KIRK: It's all right. Let him go.
CHEKOV: What could the Others do to cause such terror?
KIRK: What was it he said, pain and delight?
CHEKOV: A peculiar mixture.
KIRK: A dead and buried city on a planet in a glacial age.
CHEKOV: And the male humanoid who doesn't know the meaning of the word female.
SCOTT [OC]: Captain!

[Cave entrance]

SCOTT: Over here, sir. There's food in there and a whole pile of other stuff. A storehouse for our muscular friends.
(They step inside carefully.)

[Cave]

KIRK: I don't think so. Scotty.
(There is a pair of photoelectric cells creating an invisible trip wire across the front of the supplies.)
KIRK: Metal. Forged, tempered. Our apish friends didn't make these. What do you think?
SCOTT: It could be a warning device to keep those creatures away from the food.
KIRK: Or the food could be a lure set by the Others to bring them in here.
SCOTT: In that case, the beam would be a signal.
KIRK: And this cave a trap.
CHEKOV: If it will trap the creatures for the Others, Captain, won't it trap us, too?
KIRK: Exactly.

[Cave entrance]

KIRK: Kirk to Enterprise.
UHURA [OC]: Enterprise. Uhura here.
KIRK: Have Doctor McCoy beam down immediately.
UHURA [OC]: Aye, sir.
KIRK: Mister Chekov, you and the security team will remain here at the entrance. We'll be in constant contact with you.
CHEKOV: Aye, sir.
(McCoy and Spock beam down. Spock is in a brown overall, and has a device on his head. McCoy is holding a remote control unit with coloured buttons. He presses one and Spock turns left to face us.)
KIRK: All right, Bones. Bring him along.
SCOTT: Keep him close to the right.

[Cave]

KIRK: Ready?
(He steps across the beam and a metal shutter slams down, sealing the cave entrance. The 'elevator room' drops rapidly.)
MCCOY: Call Chekov and tell him to send my stomach down.

[Cave entrance]

CHEKOV: It might be a long wait. We may as well be comfortable.
(He uses his phaser to heat a rock, and they warm their hands in its glow.)

[Cave]

KIRK: Phasers on stun.
SCOTT: Captain, that power we picked up above, we're getting closer.
KIRK: A lot of it?
SCOTT: Enough to push this planet out of orbit.
KIRK: What source?
SCOTT: Either a nuclear pile a hundred miles across or
KIRK: Or what?
SCOTT: Ion power.
KIRK: We're slowing down.
(The door opens, and there is a woman in yellow in the corridor. She reaches to her wrist band, but Kirk stuns her first. He takes her wrist band.)

[Corridor]

KIRK: Is she all right?
MCCOY: I'll have her talking in a minute.
LUMA: You do not belong here. You are not Morg.
KIRK: Who's in charge? I wish to speak to him.
LUMA: Him? What is him?
KIRK: What have you done with Spock's brain? Where've you taken it?
LUMA: You are not Morg or Eymorg. I know nothing about a brain.
KIRK: You're lying!
MCCOY: She's not, Jim. No change in reading. She doesn't know.
KIRK: (to Scott) See what you can pick up on your communicator.
SCOTT: Aye.
KIRK: We don't want to hurt you. What is this place?
LUMA: This place is here.
KIRK: Who are you?
LUMA: I am Luma. I am Eymorg. You are not Eymorg. You are not Morg. What are you?
MCCOY: Jim, it's no use. You'll get nothing out of that one. Hers is the mind of a child.
SCOTT: Captain, I've got something, but I can't quite get a fix on it.
(Luma tries to get away, but McCoy grabs her.)
SPOCK [OC]: Fascinating. Activity without end, but with no volition.
KIRK: Spock, is that you?
SPOCK [OC]: Captain? Captain Kirk?
KIRK: Yes, Spock. Yes.
SPOCK [OC]: Captain, there is a definite pleasurable experience connected with the hearing of your voice.
MCCOY: Where are you, Spock?
SPOCK [OC]: Is that you, Doctor McCoy, and are you with the Captain?
MCCOY: Where else would I be?
SCOTT: Mister Spock, where are you?
SPOCK [OC]: Engineer Scott as well. Unfortunately, I do not know where I am.
KIRK: We'll get you, Spock. It won't be long.
SPOCK [OC]: A practical idea, Captain. It seems unlikely that I shall be able to get to you.
KIRK: Quickly!
(They head off down the corridor, Scott controlling Spock's body. Then around a corner comes a woman in purple with two Morg in uniforms.)
KIRK: There she is. That's the one. What have you done with Spock's brain?
(The woman in purple uses her wrist band to knock out the men. Only Spock is left standing.)

Captain's Log, stardate 5431.6. Immediately after making contact with Spock's brain, Doctor McCoy, Engineer Scott, and myself were taken prisoner inside a highly complex civilisation hundreds of metres below the surface of planet Sigma Draconis Seven. The primitive creature we encountered above warned us about the givers of pain and delight and the frightening consequences of being captured by them.

[Council room]

(Luma and other women are present, and occasionally giving pieces of food to the men standing around. Our landing party are still unconscious, and sitting on stools. The woman in purple comes in, and four women sit at the L shaped table. She presses the green button twice, and they wake up. All the men have belts with green buckles on them.)
KARA: What are you? Why are you here? You have something to speak?
KIRK: What have you done with Spock's brain?
KARA: We do not know Spock.
KIRK: This is Spock. You saw him on the ship. You have his brain. It must be restored to him immediately. What have you done with it?
KARA: Ah, yes, brain. You spoke to Luma also of brain, but we do not understand.
KIRK: I do not know about Luma, but you were on the Enterprise. I saw you.
KARA: I do not know these things you speak of.
KIRK: You came to my ship!
KARA: We know only here below and here above. This is our place. You are not Morg. You are stranger.
KIRK: I saw you on my ship.
MCCOY: Jim, she may not remember or even really know. Disassociation could be complete. It doesn't seem possible she could have performed surgery on Spock.
KIRK: No, it doesn't.
KARA: You hurt Luma. It is not permitted again to hurt anyone.
KIRK: Sorry. We don't want to hurt anyone.
KARA: If you wish to return to your home, you may go.
KIRK: No. We'll stay here and learn about you and tell you of us.
MCCOY: Yes, for instance, above it's cold and harsh. And below, it's warm. The air is fresh.
SCOTT: Aye. There's no sun, but there's light.
KIRK: I wish to talk to those in charge.
KARA: In charge?
KIRK: Yes, the organisers, the managers. The leader of your people.
KARA: I am leader. There is no other.
SCOTT: That's impossible. Who built the machines?
MCCOY: Who are the doctors? Who operates?
KIRK: Who controls this complex?
KARA: Control? Controller?
KIRK: Yes, the Controller. The Controller. Who controls? I would like to meet, to see him.
KARA: No. It is not permitted. Never! Controller is alone, apart. We serve Controller. No other is permitted near.
KIRK: We intend no harm.
KARA: You have come to destroy us.
KIRK: No, no, no. I promise you.
MCCOY: We just want to talk to somebody about Spock's brain. That's all.
KARA: Brain and brain! What is brain? It is Controller, is it not?
MCCOY: Yes. Yes, in a way it is. The human brain controls the individual's functions.
KIRK: Bones. Scotty. Spock's brain controls
MCCOY: It's not possible.
KIRK: Great leader. Great leader! (He kneels in front of Kara.) We come from a far place to learn from your Controller.
KARA: You lie! You know me. You have said that. You came to take back the Controller.
KIRK: He is our friend. You must take us to him. We beg you. Soon it will be too late.
LUMA: Do not take them, Kara. Do not take them to the Controller.
KARA: They will be prevented.
KIRK: You must take us.
(A single press of the green button and they collapse, writhing in agony.)
KARA: I must learn what to do. (to Luma) Come with me. You will keep them here.
GUARD: Yes, mistress.
(The women - sorry, Eymorg - leave.)

Ship's log. Lieutenant Sulu recording. I am holding the Enterprise in orbit about planet Sigma Draconis Seven. Captain Kirk's hunch that Spock's brain is on this planet appears to be correct. Ensign Chekov remains on the surface to act as liaison between the Captain and the Enterprise.

{Council room]

KIRK: I never felt anything like that. Every nerve in my body was on fire.
MCCOY: I wouldn't believe the human organism could take such pain.
SCOTT: These are on to stay for a while. Must be a magnetic lock of some kind.
KIRK: No wonder the Morgs are so obedient, and terrified.
(A Morg blocks the doorway.)
KIRK: How is this place kept functioning by the primitive minds we've met?
(Their equipment is laid out on a table, but another Morg stops Kirk getting to it.)
SCOTT: Those women could never have set up anything as complex as this has to be. Why, that takes engineering genius. But there's no sign of engineering genius in any of those women.
KIRK: They were smart enough to invent these training devices. What a way to maintain control over a man.
SCOTT: Pain and delight, he said up above.
MCCOY: I'm sure you noticed the delight aspect of this place.
KIRK: Yes, I certainly did notice those delightful aspects. But that too was strictly under command of the women.
SCOTT: How does Spock's brain fit into this?
KIRK: With a communicator, we might be able to find out. This fellow is keeping us from our property.
SCOTT: Isn't there a way to correct that situation?
KIRK: I certainly think that science might provide an answer.
MCCOY: It does, Captain.
KIRK: Agreed, Doctor.
(Kirk hits the Morg by the table while Scott and McCoy take on the one by the door. It isn't easy, but finally the Captain triumphs.)
KIRK: Science will triumph. Come on, Scotty. Bones, give them something to keep them out for a while. (into communicator) Spock. Spock. Come on, Spock. Spock, you were on this frequency, Spock.
SPOCK [OC]: Yes, Captain, I am still here. Have you returned to the Enterprise?
KIRK: No. We might be able to locate you, if you gave us some idea of what they were using you for. Is it medical?
SPOCK [OC]: I am not certain. I seem to have a body which stretches into infinity.
SCOTT: Body? Why, you have none.
SPOCK [OC]: Then what am l?
MCCOY: You are a disembodied brain.
SPOCK [OC]: Fascinating. It could explain much, Doctor. My medulla oblongata is hard at work apparently breathing, apparently pumping blood, apparently maintaining a normal physiologic temperature.
KIRK: Spock, we don't have time for that.
SPOCK [OC]: Why are you endangering your lives by coming here?
KIRK: We came to put you back. Where are you?
SPOCK [OC]: Back where?
KIRK: Back into your body. We brought it along with us.
SPOCK [OC]: Thoughtful, Captain, but probably impractical. While I might trust the doctor to remove a splinter or lance a boil, I do not believe he has the knowledge to restore a brain.
MCCOY: Thank you.
SPOCK [OC]: No denigration intended, Doctor McCoy. That skill does not yet exist in the galaxy.
KIRK: The skill to remove it exists right where we are. Restoring it must also be possible. That's why we've got to get to you as quickly as we can.
SPOCK [OC]: Captain, I appreciate the risks you are taking on my behalf, but I must insist they are worthwhile only if there is a reasonable chance for success. Let me ask you, how much time has elapsed since
KIRK: Eighteen hours and twelve minutes.
SPOCK [OC]: Doctor McCoy must've told you that twenty four hours is the maximum my body can
MCCOY: I told him.
KIRK: That leaves us exactly five hours and forty eight minutes, Spock.
SPOCK [OC]: It does seem all too brief a time to develop such skills, does it not?
KIRK: Yes. Very brief. That's why we must get to you immediately. Beam us a signal so we can home in on you.
SPOCK [OC]: Acknowledged.
SCOTT: Got it.
KIRK: Bones. (Spock's body stands up and they walk out of the room)

[Corridor]

KIRK: Oh, Spock, one question.
SPOCK [OC]: Yes, Captain.
KIRK: We've got pain-giving devices attached to us. Can you tell us how to get them off.
SPOCK [OC]: I shall give it top priority.
(They walk along.)
SPOCK [OC]: Captain, I have an answer for you. It seems your pain bands are manually controlled. The red button on a bracelet releases them. I know that does not make much sense.
KIRK: Oh, yes it does, Spock. (further along) Keep concentrating, Spock. Keep concentrating, Spock.
SCOTT: Must be in there, Captain.

[Control Room]

(Kara is in there, with her back to the door. She hears them enter, and gives them pain.)
MCCOY: Jim.. Spock. No pain.
(Kirk manages to get to the control box that McCoy dropped and get Spock's body to walk over to Kara.)
KARA: No. Go away.
(Spock holds her wrists, then finally presses the red button. The belts fly off.)
KARA: We will die. You must not take the Controller away. We will all die. The Controller is young and powerful. Perfect!
SPOCK [OC]: How very flattering.
KARA: You will give life to my people for ten thousand years to come.
KIRK: You'll find another Controller.
KARA: The old one is finished! There is no other than this and will not be another for ten thousand years.
KIRK: Spock, you're in a black box tied in with light rays into a complex control panel.
SPOCK [OC]: Fascinating.
KIRK: You say you're breathing, pumping blood, maintaining temperature? Is it possible that you're re-circulating air, running heating plants, purifying water?
SPOCK [OC]: Indeed, Captain. That is unquestionably part of what I am doing.
KARA: He must stay. He must stay!
KIRK: He will not stay. (He makes Spock release her, and grabs her himself, taking off her bracelet.) Now, you took his brain. You will put it back. How did you do it?
KARA: I do not know.
MCCOY: She couldn't, Jim. Her mind is functioning on a very simple level. Mental faculties here seem to be almost atrophied because of non-use.
KIRK: She was on the Enterprise. She must have done it. How did you do it?
KARA: It was the old knowledge.
KIRK: How do you get the old knowledge?
KARA: I put upon my head the Teacher.
KIRK: What is the Teacher?
KARA: The great Teacher of all the ancient knowledge.
(There is a transparent helmet with what look like a whole lot of syringes sticking through it.)
SPOCK [OC]: If I may explain, Captain. She refers to the tape storehouse of knowledge of the builders of this place. I scan it. A most impressive store.
KIRK: How does it work? Show us.
KARA; I cannot.
KIRK: You must tell us.
KARA: I cannot. Only by command of the ancients may I understand.
KIRK: How does it work? Show us! We'll protect you.
SPOCK [OC]: It is a device with feeding circuits. They lead into the mind of the priestess leader. Its use is strictly predetermined by the builders.
(Kirk forces her into the helmet.)
KARA: No! The knowledge is forbidden! I must not know the secret! I will be punished!
(A control panel comes on and she goes quiet.)
KARA: (confident, assured) Gentlemen, the Controller's explanation of the functioning of the Teacher is essentially correct. However, he is giving no credit to me. I provide the means whereby the knowledge is used. Without me, Captain
MCCOY: Without you there could be no delicate miracle that kept Spock's brain alive.
KARA: Thank you, Doctor. That was very gracious.
MCCOY: Yes. From the very first, I appreciated your ability.
KARA: Good, Captain Kirk. Then you also appreciate that without the Teacher, I would not have the knowledge to use that which you have thoughtfully provided.
(She points a phaser at him.)
SCOTT: That phaser is set to kill.
KARA: So it is. That is the knowledge you have brought me. Do not move. If your weapon kills, it will kill you.
KIRK: We're not the first to bring you the knowledge of killing. If you continue, you'll kill Spock.
KARA: The Controller die? The Controller will live for ten thousand years, and we shall give him all our devotion.
KIRK: But Spock will be dead. His body's dying this minute.
KARA: Why do you not understand that the need of my people for their Controller is greater than your need for your friend.
KIRK: No one may kill a man. Not for any purpose. It cannot be condoned.
(He reaches for the phaser.)
KARA: Do not! I do not know killing. I do not wish to kill.
(Scott groans and faints, distracting her so Kirk can grab the phaser.)
KARA: The commandment must be fulfilled.
KIRK: You must help us. When you came to the ship, you had the knowledge. Yet, when we came here, you didn't.
KARA: Correct.
KIRK: How long does the knowledge last?
KARA: Three of your hours.
MCCOY: It would be just enough time.
KIRK: If you had the knowledge, could you restore what you've taken?
KARA: I would not.
KIRK: You must help us. You must restore with that knowledge what you have taken.
KARA: No!
KIRK: You must put back what you have taken.
KARA: I will not betray my people. The Controller will stay.
MCCOY: Jim, it worked for her. It might work for me.
SPOCK [OC]: She is an alien. The configurations of her brain are different. It could cause irreparable damage to your human brain, Doctor.
MCCOY: I'm a surgeon already. If I could learn these techniques, I might be able to retain them.
SPOCK [OC]: Captain, you might lose the doctor that way.
MCCOY: He might, but we're sure to lose you if I don't try.
SPOCK [OC]: I cannot allow you to jeopardise your life for me.
MCCOY: Spock, didn't you hear? I might be able to retain and bring these techniques to the world. Jim, isn't it worth that risk? Wouldn't you insist upon taking such a risk yourself?
KIRK: Go ahead, Doctor. Put the Teacher on.
KARA: No!
(McCoy goes over to the device, and Kirk adjusts it onto his head. McCoy winces in pain as knowledge is fed into his brain, then falls to his knees.)
MCCOY: Of course. Of course. A child could do it. A child could do it.

Captain's log, Stardate 5432.3. Doctor McCoy is proceeding to restore Spock's brain. Our problem, we do not know how long his increased surgical knowledge will stay with him. Any additional attempt to use the teaching device is impossible. It would kill my medical officer.

[Control room]

(The top of Spock's head is concealed by a wall, which McCoy is working behind.)
SCOTT: I've never seen anything like it. He's operating at warp speed. I'd like a try at that teacher myself.
KARA: You will have him back and we will be destroyed.
KIRK: No. You won't be destroyed. You'll be without your Controller for the first time, but you'll be much better off, I think.
KARA: We will die.
KIRK: No, you'll live and develop as you should have. All this shouldn't have been done for you. Now the women here below and the men here above will control together.
KARA: They will not help us without the pain.
KIRK: There are other ways. You'll discover them. You must move to the surface, you understand.
KARA: We will die above in the cold.
KIRK: No, you won't. You'll learn to build houses, to keep warm, to work. We'll help you for a while. Humans have survived under worse conditions. It's a matter of evolution. You'll be fine.
(McCoy is starting to pause and think.)
SCOTT: Captain Kirk!
KIRK: What is it?
SCOTT: He's forgetting.
MCCOY: I can't. I
KIRK: Bones? Bones?
MCCOY: All the ganglia, the nerves. There are a million of them. What am I supposed to do? What am I supposed to do?
KIRK: Bones, you can't stop now.
MCCOY: I'm trying to thread a needle with a sledgehammer. What am I supposed to do? I can't remember. I don't remember.
KIRK: Bones?
MCCOY: No one can restore a brain.
KIRK: You could. A while ago it was child's play.

Captain's log, supplemental. Our race against time to save Spock's life may prove futile. Doctor McCoy has lost the surgical knowledge he obtained from the teacher. He has been drawing on his own skills and surgical techniques in an attempt to continue the operation, but he is faltering and uncertain. In a desperate hope that he can draw on Spock's brain for assistance, I instructed Doctor McCoy to give priority to connecting Spock's vocal chords.

[Control room]

KIRK: Well?
MCCOY: He's dying, and I can't stop it.
SPOCK: (hoarse) Yes. Doctor McCoy.
MCCOY: Spock?
SPOCK: If you will finish reconnecting my speech centre, I might be able to help.
MCCOY: Speech centre.
SPOCK: Yes. That's correct. One thing at a time. Ah, ah, mmm. (normal voice) That's better. Now, Doctor. Try the sonic separator.
MCCOY: Sonic separator.
SPOCK: Yes, I believe I already have some sensation of feeling. Please stimulate the nerve endings and observe the physical reactions, one by one. In each case, I shall tell you when the probe is correct. You will then seal using the tri-laser connector.
MCCOY: Tri-laser connector. Ready?
SPOCK: Ready.
MCCOY: Right forefinger.
SPOCK: (twitching) Correct.
MCCOY: Right wrist.
SPOCK: Correct.
MCCOY: Right elbow.
SPOCK: Correct. Very good, Doctor.
MCCOY: I'll never live this down. This Vulcan is telling me how to operate.
(Later)
MCCOY: Closed.
KIRK: Well?
MCCOY: How do I know? I could have made a thousand mistakes. Sealing nerve endings, joining ganglia. The fluid balance is correct, but I don't know.
(Spock sits up and stretches.)
SPOCK: Congratulations, Doctor. And thank you.
KIRK: How do you feel, Spock?
SPOCK: On the whole, Captain, I believe I am quite fit. Fascinating. A remarkable example of a retrograde civilisation. At the peak, advanced beyond any of our capabilities and now operating at this primitive level which you saw. And it all began thousands of years ago when a glacial age reoccurred. This underground complex was developed for the women. The men remained above, and a male-female schism took place. A fascinating cultural development of a kind which never
MCCOY: I knew it was wrong. I shouldn't have done it.
KIRK: What's that?
MCCOY: I should have never reconnected his mouth.
(A slanted eyebrow hits the ceiling.)
KIRK: Well, we took the risk, Doctor.
SPOCK: (to Kara, amid laughter) As I was saying, a fascinating cultural development of the kind which hasn't been seen in ages. The last such occurrence took place on old Earth, when the Romans were warring with the ....