(Kirk and Spock are standing by a large purple boulder.)
SPOCK: Our scanner survey was correct, Captain. There it is. Pure tritanium.
KIRK: Fantastic. 20 times as hard as diamond.
SPOCK: Twenty one point four times as hard, to be exact.
KIRK: Thank you, Mister Spock. (into communicator) Scotty, you can mark this vein as confirmed. Inform Starfleet I recommend that they dispatch a survey vessel immediately.
(Unseen by the landing party, a cloud of smoke is coming out of another rock and heading for them.)
SCOTT [OC]: Acknowledged, Captain. They'll send one fast enough for this rich a find.
SPOCK: We won't be able to break it, Captain. I'll phaser off a specimen.
(He does so, and the smoke retreats.)
KIRK: Lesley.
(He is handed a pair of tongs to pick up the sample with.)
KIRK: Do you smell that? A sweet odour like honey. It was years ago, on another planet. A thing with a an odour like that.
SPOCK: We're in the growing season in this hemisphere of this planet. There are doubtless many pollen aromas.
KIRK: Rizzo.
RIZZO: Yes, sir?
KIRK: Take your men. Make a swing around our perimeter. Scan for dikironium in the atmosphere. Set your phasers on disrupter-B. If you see any gaseous cloud, fire immediately. You're on Red Alert. Make a sweep.
SCOTT [OC]: Ready to beam back aboard, Captain?
KIRK: Negative, Scotty. We're checking something out.
SCOTT [OC]: The USS Yorktown is expecting to rendezvous with us in less than eight hours, Captain. That doesn't give us much time.
KIRK: Acknowledged. Continue standing by. Kirk out.
SPOCK: Captain, dikironium exists only in laboratory experiments.
KIRK: It's gone. I could have been wrong. The last time I caught an odour like that was eleven years ago.

[Clearing]

(The three red-shirts have run into a clearing.)
RIZZO: Seemed to read dikironium for a minute, and then I lost it. It's almost like something out there knows I'm scanning it. It kind of keeps changing itself into something different. That isn't possible. Nothing can do that.
(All together now - It's Behind You! The other two security men fall to the ground, choking in the cloud. Rizzo can't get a clear shot.)
RIZZO: Captain?

[Boulder]

KIRK: Kirk here.

[Clearing]

RIZZO: Captain.

[Boulder]

RIZZO [OC]: There's a strange cloud, sir.

[Clearing]

(It reaches him and he starts choking too)
RIZZO: Cloud, cloud.

[Boulder]

KIRK: Fire into it immediately!
RIZZO [OC]: Help me. Help!

[Clearing]

(But by the time they get there, the cloud has gone.)
KIRK: Spock. Dead. And you'll find every red corpuscle gone from their body.
SPOCK: Rizzo's alive, barely.
KIRK: Kirk to Enterprise. Scotty, lock in on us. Medical emergency.
SPOCK: You think you know what it was, Captain?
KIRK: Something that can't possibly exist, but it does.

Captain's log, stardate 3619.2. With the mysterious death of two crewmen, all personnel on the planet have been evacuated back to the ship.

[McCoy's office]

CHAPEL: Autopsy report, Doctor.
KIRK: How's Ensign Rizzo?
CHAPEL: Still unconscious, sir.
MCCOY: Transfusions?
CHAPEL: Continuing as rapidly as possible. His blood count is still sixty percent less than normal. (leaves)
KIRK: Kirk to bridge.
SPOCK [on monitor]: Spock here. Ready to leave orbit, Captain.
KIRK: Hold your position.
SCOTT [on monitor]: Cutting in if I may, Captain. The USS Yorktown is expecting to rendezvous with us in less than seven hours.
KIRK: Then you'll inform them that we might be a little late.
MCCOY: Jim, the Yorktown's ship surgeon will want to know how late. Those vaccines he's transferring to us are highly perishable.
SPOCK [on monitor]: Spock again, Captain. Those medical supplies are badly needed on planet Theta Seven. They are expecting us to get them there on time.
KIRK: Gentlemen, we are remaining in orbit until I find out more about those deaths, on my responsibility. I am perfectly aware that it might cost lives on Theta Seven. Kirk out. Autopsy report.
MCCOY: You saw their colour. There wasn't a red corpuscle left in their bodies.
KIRK: Marks, cuts, incisions of any kind?
MCCOY: Not a one. What happened is medically impossible.
KIRK: I suggest you look at the record tapes of past similar occurrences. You'll find the USS Farragut lists casualties eleven years ago from exactly the same impossible causes.
MCCOY: Thank you, Captain. I'll check those tapes immediately.
KIRK: First, can you bring Ensign Rizzo to consciousness for a moment?
MCCOY: Yes, but it
KIRK: Will it hurt him if you do so?
MCCOY: In his present condition, I don't think it would make much difference.
KIRK: Then do so.

[Sickbay]

CHAPEL: Transfusion completed, sir. His pulse and respiration are still far below normal.
MCCOY: Give him one cc of cordazine, nurse.
CHAPEL: Yes, sir.
KIRK: Rizzo. This is the captain. Can you hear me? Do you remember what happened to you?
RIZZO: Remember. I'm cold. I'm so cold.
KIRK: You were attacked by something. When it happened, did you notice an odour of any kind? Rizzo. Rizzo! Do you remember a sickly sweet odour? Did you smell it?
RIZZO: Yes. Yes. A smell. A strange smell. It was like being smothered in honey.
KIRK: Did you feel a presence, an intelligence?
RIZZO: It was trying to draw strength from us. I felt it. It was, it was, it was there.
MCCOY: He's beginning to sleep again. I can't risk another shot.
KIRK: He's already told me what I wanted to know.
MCCOY: I wouldn't depend too much what he says in that half-conscious state. He could be dreaming, saying what he thought you wanted to hear.
KIRK: You check those record tapes. I want your medical analysis as quickly as possible. (leaves)
CHAPEL: What's with the captain? I've never seen him like that before.
MCCOY: I intend to find out. I'll be in the medical record library.

[Bridge]

UHURA: Oh, Captain. Subspace message from Starfleet. They're inquiring
KIRK: Not now. Have the security duty officer report to me immediately.
UHURA: Aye, sir.
KIRK: Spock?
SPOCK: Continuing scanning. Still no readings of life forms on the planet.
KIRK: Let's assume that it's something so completely different that our sensors wouldn't identify it as a life form.
SPOCK: You mentioned dikironium, Captain.
KIRK: Suppose it was composed of that rare element. A strange, gaseous creature.
SPOCK: I've scanned for that element, Captain. There's no trace of dikironium on the planet surface or in the atmosphere.
KIRK: Suppose it camouflaged itself. Let's assume that it's intelligent, that it knows we're looking for it.
SPOCK: To hide from a sensor scan, it would have to be able to change its molecular structure, like gold changing itself to lead or wood changing itself to ivory.
KIRK: You've just suggested something that never occurred to me. It may provide some answers to a tape record which I think you'll find Doctor McCoy is looking at this very moment.
SPOCK: Chekov, take over on scanner.
(As Spock steps into the turbolift, Garrovick steps out onto the bridge.)
GARROVICK: Ensign Garrovick reporting, sir.
KIRK: Are you the new security officer?
GARROVICK: Yes, sir.
KIRK: Was your father
GARROVICK: Yes, sir, but I don't expect any special treatment on that account.
KIRK: You'll get none aboard this ship, Mister.
GARROVICK: Yes, sir.
UHURA: Captain, I have a report on Ensign Rizzo. He's dead, sir.
KIRK: You knew Rizzo?
GARROVICK: Yes, sir. We were good friends, graduated the Academy together.
KIRK: You'll get a crack at what killed him. Interested?
GARROVICK: Yes, I am, sir.
KIRK: I want four men armed with phaser two set for disrupter effect. Join me in the transporter room in five minutes. You'll accompany me to the planet surface.
GARROVICK: Yes, sir.

[Planet surface]

GARROVICK: Reading is changing, sir.
KIRK: Spock was right. Notice the molecular shift? 
GARROVICK: Dikironium reading now, sir. Bearing ninety four mark seven, angle of elevation six degrees. Holding steady.
KIRK: Over that rise. Take two men, circle around to the left. I'll take the other two and go the other way. That creature is dangerous. If you see it, fire full phasers.
GARROVICK: Yes, sir.
KIRK: Swensen, Bardoli come with me.
(Garrovick and his group go into a clearing, and the cloud emerges. Garrovick fires at it after a slight hesitation.)
KIRK: A phaser! Come on! (arriving at the scene) Garrovick, did you?
(But then he sees the other two security men, lying on the ground, skin pale as snow.)

Captain's log, stardate 3619.6. One of the men in critical condition, the other is dead. And I, I am now even more convinced that this is not only an intelligent creature, but the same which decimated the crew of the USS Farragut eleven years ago in another part of the galaxy. Both Spock and McCoy are doubtful of this, and I sense they also doubt my decision to stay and fight the thing. Why am I keeping the ship here?

[Briefing room]

(Kirk is already there when Spock, McCoy and Garrovick enter.)
KIRK: Mister Garrovick, we've studied your report. Mister Spock, begin.
SPOCK: What was the size of the thing you saw, Ensign?
GARROVICK: I'd say it measured from ten to sixty cubic metres, sir. It varied in size, fluctuated as it moved.
SPOCK: Composition?
GARROVICK: It was like a, a gaseous cloud. Parts of it I could see through. Other parts were more dense.
MCCOY: Ensign, did you sense any intelligence in this gaseous cloud?
GARROVICK: Did I what, sir?
MCCOY: Did you get any subconscious impressions that this was a creature. A living, thinking thing, rather than just a strange cloud of chemical elements?
GARROVICK: No, sir.
KIRK: But you didn't come to actual contact with it, did you?
GARROVICK: No, sir. I was furthest away from it. It seemed to come out of nowhere, hovered for a moment, then moved toward my men. It was fast, incredibly fast.
KIRK: Did you say it hovered?
GARROVICK: Yes, sir.
KIRK: You did fire at it, didn't you?
GARROVICK: Yes, sir, I did.
KIRK: What distance were you from the creature?
GARROVICK: About twenty yards, sir.
KIRK: You fired at a large, hovering target at that distance and missed?
GARROVICK: Yes. I, er, well, I didn't fire while it was hovering, sir.
KIRK: You mean you froze?
GARROVICK: No, sir. I didn't exactly freeze.
KIRK: What exactly were you doing?
GARROVICK: Well, I was startled for a second. And then by the time I fired, the thing was already moving.
KIRK: Do you have any further information?
GARROVICK: No, sir.
KIRK: Do you gentlemen have any further questions?
GARROVICK: I only hesitated for a moment, sir. I'm sorry.
KIRK: Ensign, you're relieved of all duties and confined to quarters until further notice.
GARROVICK: Yes, sir. (leaves)
MCCOY: You were a little hard on the boy, Jim.
KIRK: He froze. One man was killed. Another may die.
SPOCK: Captain, scientifically
KIRK: You'll both be filing reports. Make your comments and recommendations then.

[Bridge]

SCOTT: Captain, while we're waiting I've taken the liberty of cleaning the radioactive disposal vent on number two impulse engine, but we'll be ready to leave orbit in under half an hour.
KIRK: We're not leaving orbit, Mister Scott. Not that quickly.
UHURA: Captain, the Yorktown requesting information on how soon we expect to rendezvous with them.
KIRK: Thank you.
SCOTT: The medicine for Theta Seven colony is not only needed desperately and has limited
KIRK: I'm aware of the situation, Engineer, and I'm getting a little tired of my senior officers conspiring against me. Forgive me. Perhaps I shouldn't have used the word conspire.
SCOTT: Agreed, sir.
KIRK: Scanner readings?
CHEKOV: Nothing, sir. Continuing to scan.
KIRK: Are you aware it can change its molecular structure?
CHEKOV: Yes, sir.
KIRK: Are you scanning for any unusual movement?
CHEKOV: Yes, sir.
KIRK: Any type of gaseous cloud?
CHEKOV: We've run a full scanner probe twice.
KIRK: Then run it twenty times if that's what it takes!

[McCoy's office]

SPOCK: I hope I'm not disturbing you, Doctor.
MCCOY: Interrupting another autopsy report is no disturbance, Mister Spock. It's a relief.
SPOCK: I need your advice.
MCCOY: Then I need a drink.
SPOCK: I do not understand your reasoning.
MCCOY: You need advice from me? You must be kidding.
SPOCK: I do not joke, Doctor. Perhaps I should rephrase my statement. I require an opinion. There are many aspects of human irrationality I do not yet comprehend. obsession, for one. The persistent, single-minded fixation on one idea.
MCCOY: Jim and his creature?
SPOCK: Precisely. Have you studied the incident involving the USS Farragut?
MCCOY: No. With all these deaths and injuries, I've only had a chance to scan the tapes. There are eight or ten hours of record tape there.
SPOCK: Fortunately, I read somewhat faster. In brief, Doctor, nearly half the crew and the captain were annihilated. The captain's name was Garrovick.
MCCOY: The same as our Ensign.
SPOCK: His father. Among the survivors was a young officer on his first deep-space assignment, James T. Kirk. And there is still more. I suggest you study this.
(Spock hands over a record tape.)

[Kirk's quarters]

(The Captain is lying on his bed, staring at the ceiling)
KIRK [OC]: Personal log, stardate 3620.7. Have I the right to jeopardise my crew, my ship for a feeling I can't even put into words? No man achieves Starfleet command without relying on intuition, but have I made a rational decision? Am I letting the horrors of the past distort my judgment of the present?
MCCOY: Mind if I come in?
(Kirk gets up and goes to his desk.)
KIRK: Kirk to bridge. Scanning report.
CHEKOV [OC]: Continued scanning, sir. No unusual readings.
KIRK: Maintain search. Kirk out. It can't have just vanished.
MCCOY: Sometimes they do, if we're lucky. Monsters come in many forms. You know the greatest monster of them all, Jim? Guilt.
KIRK: Get to the point.
MCCOY: Jim, When a young officer is exposed to unknown dangers for the first time, he's under tremendous emotional stress. Now we all know that.
KIRK: Ensign Garrovick is a ship-command decision. You're straying out of your field, Doctor.
(He returns to his bed.)
MCCOY: Am I? I was speaking of Lieutenant James T. Kirk of the starship Farragut. Eleven years ago, you were the young officer at the phaser station when something attacked. According to the tapes, this young Lieutenant Kirk insisted upon blaming himself.
KIRK: Because I delayed in firing at it.
MCCOY: You had a normal emotion. You were startled. You delayed firing for a grand total of perhaps two seconds.
KIRK: If I hadn't delayed, it would have been killed.
MCCOY: The ship's exec didn't seem to think so. His log entry was quite clear on the subject. Lieutenant Kirk is a fine young officer who performed with uncommon bravery.
KIRK: Don't you understand? It killed two hundred crewmen.
MCCOY: Captain Garrovick was very important to you, wasn't he, Jim?
KIRK: Yes. He was my commanding officer from the day I left the Academy. One of the finest men I ever knew. I could have killed that thing if I'd fired soon enough the first time.
MCCOY: You don't know that, Jim. You don't know that any more than you know that Garrovick could have destroyed it.
KIRK: I can't help how I feel. There's an intelligence about it, Bones. A malevolence. It's evil. It must be destroyed.
MCCOY: To be so obsessed.
KIRK: Obsessed?
MCCOY: That you could destroy yourself, your career, a young boy who reminds you of yourself eleven years ago.
KIRK: Don't push our friendship past the point where I have to take official
MCCOY: I'm not, Jim. This is professional, Captain. I am preparing a medical log entry on my estimation of the physical and emotional condition of a starship captain. Which requires a witness of command grade.
(McCoy goes to the door and opens it to admit Spock.)
KIRK: Do I take it, Doctor, Commander, that both of you or either of you consider me unfit or incapacitated?
SPOCK: Correctly phrased, Captain. As recommended in the manual. Our reply, also as recommended, is, sir, we have noted in your recent behaviour certain items, which, on the surface, seem unusual. We respectfully ask permission to inquire further
KIRK: Blast it! Forget the manual! Ask your questions.
SPOCK: Sir, the USS Yorktown is waiting now at the rendezvous point. It carries perishable drugs
KIRK: Skip the recitation, Spock. I know the facts.
MCCOY: They need those vaccines on Theta Seven, Captain. Now why are we delaying here?
KIRK: Because I'm convinced that this is the same creature that attacked the Farragut eleven years ago.
SPOCK: Creature, Captain?
KIRK: My report is on the tapes. As it attacked us eleven years ago, as I lost consciousness, I could feel the intelligence of the thing. I could sense it thinking, planning.
SPOCK: You say you could sense its intelligence, Captain? How did it communicate with you?
MCCOY: You state that it happened just as you lost consciousness. A semiconscious mind is a very tricky thing. A man never knows how much is real or how much is imagination.
KIRK: Whatever it is, Doctor, whatever it is, wouldn't you call it deadly?
MCCOY: Yes, there's no doubt about that.
KIRK: And what if it is the same creature that attacked eleven years ago from a planet over a thousand light years from here?
SPOCK: Obviously, Captain, if it is an intelligent creature, if it is the same one, if it therefore is capable of space travel, it could pose a great threat to inhabited planets.
KIRK: A lot of ifs, I agree, but in my command judgment, they out weigh other factors. Intuition, however illogical, Mister Spock, is recognized as a command prerogative.
MCCOY: Jim, we're not trying to gang up on you.
KIRK: And you haven't, Doctor. You've expressed the proper concern, you've asked the proper questions. You've both done your duty. Now may I ask what medical log entry you intend to make?
MCCOY: At this point, my medical log remains open.
KIRK: In that case, gentlemen
CHEKOV [OC]: Bridge to Captain. Come in. 
KIRK: Kirk here.
CHEKOV: I have a reading on the whatever it is, Captain. Leaving the planet surface, heading into space.
KIRK: All decks, Red Alert. Red alert. Prepare to leave orbit.

[Bridge]

SCOTT: Captain, we can't maintain warp eight speed much longer. Pressures are approaching the critical point.
KIRK: Range, Mister Chekov?
CHEKOV [OC]: Point zero four light years ahead. Our phasers won't reach it, sir.
SPOCK: We are barely closing in on it, Captain. We could be pursuing it for days.
KIRK: If necessary. Do what you can to increase our speed, Scott.
SCOTT: Aye, sir.
KIRK: Extreme magnification, Mister Chekov.
CHEKOV: Magnification twelve. There, sir. Got it.
KIRK: Spock, how do you read that?
SPOCK: Conflicting data, Captain. It seems to be in a borderline state between matter and energy. Elements of both. It could possibly use gravitational fields for propulsion.
KIRK: And you don't find that sophisticated, Mister Spock?
SPOCK: Extremely efficient, Captain. Whether that indicates intelligence is another matter.
CHEKOV: Open hatch on impulse engine number two. Mister Scott was doing an AID clean-up on it.
KIRK: We won't be using the impulse engines. Turn the alarm off.
CHEKOV: Aye, sir.
SCOTT: Captain, we can't do it. If we keep this speed, we'll blow up any minute now.
(Scott looks frantic, Spock almost concerned, everyone else is worried. Kirk looks as if he might burst into tears of frustration.)
KIRK: Go to warp six.

[Garrovick's quarters]

CHAPEL: Hi. Everyone else is at alert station, so I brought you some dinner.
GARROVICK: I'm not hungry.
CHAPEL: Doctor's orders.
GARROVICK: What's happening?
CHAPEL: Are we still chasing that thing half way across the galaxy? Yes. Has the captain lost his sense of balance? Maybe. Is the entire crew about ready to explode? Positively. You're lucky you're out of it.
GARROVICK: What do you mean, out of it? I caused it. You know that, too, don't you? If I'd fired my phaser quickly enough on Argus Ten, this wouldn't have happened.
CHAPEL: You know, self-pity's a terrible first course. Why don't you try the soup instead?
GARROVICK: I told you, Christine, I'm not hungry.
CHAPEL: Doctor McCoy thought you might say something like that. This is his officially logged prescription for you. It has one word on it. Eat. Now if you don't follow his orders, Doctor McCoy could and possibly would have you hauled down to Sickbay and fed intravenously.
(She leaves, carrying the record tape.)

[McCoy's office]

(Chapel puts the record tape in McCoy's in-tray.)
MCCOY: What's that?
CHAPEL: Hmm? (picks up the tape again) This?
MCCOY: (reading) A survey on Cygnian Respiratory Diseases? I thought you took Garrovick some food. What were you doing with this?
CHAPEL: Applying psychology.

[Bridge]

CHEKOV: The creature is slowing. It's down to warp two.
KIRK: Reduce speed. Approach slowly.
CHEKOV: I don't understand. It was outrunning us.
KIRK: Maybe it's decided to fight. Phasers ready?
CHEKOV: Phasers show ready, sir.

[Garrovick's quarters]

(Garrovick takes the lid off his meal and throws it across the room. It knocks the switch on his ventilation filter to 'bypass'.)
KIRK [OC]: Battle stations. All decks to battle stations. This is not a drill. All decks to battle stations.
(Garrovick dashes out into the corridor.)

[Bridge]

CHEKOV: It's coming to a full halt, sir. Magnification one.
KIRK: Move in closely, Mister Chekov. Sublight one quarter speed.
GARROVICK: Captain, request permission to return to my post.
(He is totally ignored.)
CHEKOV: Within phaser range, sir.
KIRK: Lock all phasers on target.
CHEKOV: Locked on target.
KIRK: Fire phasers, Mister Chekov.
(The beams of deadly light go straight through the cloud.)
CHEKOV: Phasers ineffectual, sir.
KIRK: Photon torpedoes. Minimum spread pattern.
CHEKOV: Minimum pattern ready, sir.
KIRK: Fire photon torpedoes.
(The ship is rocked by the blasts at such close quarters.)
UHURA: There. It's coming, sir.
KIRK: Deflectors up.
CHEKOV: Deflectors up, sir.
SPOCK: The deflectors will not stop it, Captain.
SCOTT: That's impossible.
SPOCK: I should have surmised this. For the creature to be able to use gravity as a propulsive force, it would have to have this capacity.
CHEKOV: Five seconds to contact. All hatches and vents secure. All lights on the board show green. Sir! The number two impulse vent! we have a red light!
KIRK: (over Chekov's speech) Lieutenant Uhura, all decks (rest of speech lost under Chekov's increasing volume)
SCOTT: Captain, something's entered through the number two impulse vent.
KIRK: Negative pressure in all ship's vents. Alert all decks.

[Briefing room]

KIRK: Report.
SCOTT: When it entered impulse engine number two's vent, it attacked two crewmen. It then got into the ventilating system, and now we have air for only two hours.
KIRK: Bones?
MCCOY: One man has a chance for survival. The other is dead. You can add that little price tag to your monster hunt.
KIRK: That's enough, Bones.
MCCOY: It's not enough! You didn't care as long as you could hang your trophy on the wall. Well, it's not on it, Captain, it's in it.
SPOCK: May I suggest that we no longer belabour the question of whether or not we should have gone after the creature. The matter has now been rendered academic. The creature is now after us.
MCCOY: Creature, Mister Spock?
SPOCK: It turned and attacked, Doctor. Its method was well-considered and intelligent.
KIRK: Yes, well, it could have been many light years away from us. Instead it chose to turn and attack here. Why?
SPOCK: Impossible to tell, Captain, until I can make a closer survey of the creature.
KIRK: Scotty, try flushing the radioactive waste into the ventilation system. See what effect that has.
SCOTT: Aye. (leaves)
MCCOY: I'm sorry, Jim. I was wrong. (leaves)
SPOCK: Captain, the creature's ability to throw itself out of time sync makes it possible for it to be elsewhere in the instant the phaser hits. There is therefore no basis for your self-recrimination. If you had fired on time and on target eleven years ago, it would have made no more difference than it did an hour ago. Captain Garrovick would still be dead. The fault was not yours, Jim. In fact, there was no fault.
KIRK: If you want to play analyst, Spock, use someone else, not me. My concern is with the ship and the crew.

[Garrovick's quarters]

GARROVICK: Come in.
SPOCK: Ensign, am I correct in my assumption that you've been disturbed by what you consider to be a failure on your part? (a nod) I would like you to consider that the hesitation for which you are blaming yourself is an hereditary trait of your species. When suddenly faced by the unknown or imminent danger, the human will experience a split second of indecision. He hesitates. Do I have your attention, Ensign?
GARROVICK: Yes, sir.
SPOCK: I know you would prefer to wallow in emotion rather than
GARROVICK: Mister Spock, it's very kind of you to come here
SPOCK: Kindness, Mr. Garrovick, is another human emotion, and I believe we have enough of that. I simply would like you to accept the fact that your reaction has its basis in physio. (suddenly stops and sniffs) Do you smell something?
GARROVICK: Sir, it's coming through the vent.
SPOCK: Get out of here! I'll attempt to seal it off.
(Spock literally throws Garrovick out into the corridor. He then goes to the vent, but the damaged switch breaks off in his hand.)

[Corridor]

GARROVICK: (into intercom) Sir, the creature's in my cabin. It's got Mister Spock.

[Bridge]

KIRK: On my way, Garrovick. Security to three four one. Medical alert. Scotty, reverse cabin pressure three four one.
(He does so, and the gas is sucked back into the vent.)

[Corridor]

KIRK: Security, hold it. Tricorder.
MCCOY: Jim, Spock may be dying.
KIRK: If we let that thing into the ship, he'll have a lot of company.
GARROVICK: I must have jammed the vent control when I hit it.
KIRK: See if the reverse pressure has pulled it back into the ventilation system.
GARROVICK: He saved my life, Captain. I should be lying dead in there, not him.
(The cabin door opens.)
SPOCK: Fortunately, neither of us is dead, Ensign. The reverse pressure worked. The vent is closed.
KIRK: Don't misunderstand my next question. Mister Spock, why aren't you dead?
MCCOY: It's that green blood of his.
SPOCK: My haemoglobin is based on copper, not iron.
MCCOY: I'll bet he left a bad taste in the creature's mouth, too.
SPOCK: Colloquially expressed, but essentially correct.
KIRK: Yes. The scent is different. I think I understand something now.
SPOCK: Do you believe you're in communication with the creature?
KIRK: I don't know what it is, Mister Spock, but you remember I said the thing was alive. It may not be communication as we understand it, but I did know it was alive and intelligent, and I think I know something else now.
SCOTT [OC]: Engineering to Captain Kirk. Engineering to Captain Kirk.
KIRK: Kirk here.
SCOTT [OC]: Scott, Captain. The creature's moving back toward the number two impulse vent. The radioactive flushing may be affecting it.
KIRK: Open the vent. On my way to the bridge. Kirk out. Ensign Garrovick.
GARROVICK: Yes, sir.
KIRK: You were on the bridge when we were attacked.
GARROVICK: Yes, I'm sorry, sir. I know I was confined to quarters, but when the alert sounded
KIRK: Very commendable, Ensign. What was your impression of the battle?
GARROVICK: I don't understand, sir.
KIRK: I'm asking for your military appraisal of the techniques used against the creature.
GARROVICK: Ineffective, Captain. I realise, Captain, you did everything you could do. I know that. It's just that nothing works against a monster that can do the things that thing does.
KIRK: And Ensign, what is your appraisal of your conduct on the planet?
GARROVICK: I delayed firing.
KIRK: If you hadn't delayed firing? No difference, Ensign. No weapon known would have made any difference. Then or eleven years ago. Report for duty, Ensign.
GARROVICK: Yes, Captain. Thank you, sir.

[Bridge]

KIRK: Report, Mister Chekov.
CHEKOV: Results positive, Captain. The creature has left the ship at high warp speed and is already nearly out of scanner range. The way that thing can move, Captain, I wouldn't believe it.
KIRK: Direction, Mister Spock.
SPOCK: It was bearing one two seven mark nine, but I've lost it now.
KIRK: (into intercom) Mister Scott, I'll need all the speed you can deliver. Keep at it until we begin to shake apart. Kirk out. I believe I know where it's going.
SPOCK: It has changed course before to mislead us, Captain. Logic would dictate that
KIRK: No, I'm playing intuition. Mister Chekov, compute a course for Tychos star system.
CHEKOV: Computed and on the board.
KIRK: Ahead full.
CHEKOV: Ahead full, sir.
KIRK: Lieutenant Uhura, contact Starfleet and the USS Yorktown.
UHURA: Frequency open and clear, sir.
KIRK: Inform them that we are pursuing the creature to planet four of that system. That's the location of its attack on the USS Farragut eleven years ago.
SPOCK: I do not understand, Captain.
KIRK: In Garrovick's quarters, I said the scent of the creature was somehow different. Something in my mind said home.
SPOCK: And you know where home is, Captain?
KIRK: Yes, I think I do. I don't know how I know, but home is where it fought a starship once before. Ito Uhura) Inform them of our tactical situation and inform them I'm committing this vessel to the destruction of the creature. We will rendezvous. Round-trip time, Mister Chekov.
CHEKOV: One point seven days, sir.
KIRK: We will rendezvous with the USS Yorktown in forty eight hours.
(later)
MCCOY: I assume that you now believe we should pursue the creature and destroy it.
SPOCK: Precisely.
KIRK: You don't agree with Mister Spock?
MCCOY: It's the time factor that bothers me. Those drugs are perishable.
SPOCK: Doctor, evidence indicates the creature is here to spawn. If so, it will reproduce by fission, not just into two parts, but thousands.
KIRK: Antimatter seems our only possibility.
SPOCK: An ounce should be sufficient. We can drain it from the ship's engines and transport it to the planet surface in a magnetic vacuum field.
KIRK: Contact medical stores. I want as much haemoplasm as they can spare in the transporter room in fifteen minutes.
GARROVICK: Yes, sir.
MCCOY: I presume you intend to use that haemoplasm to attract the creature?
KIRK: We must get it to the antimatter. It seems attracted to red blood cells. What better bait could we have?
SPOCK: There is still one problem, Captain.
KIRK: The blast, yes.
SPOCK: Exactly. A matter-antimatter blast will rip away half the planet's atmosphere. If our vessel is in orbit and encounters those shock waves
KIRK: A chance we'll have to take, Mister Spock.
SPOCK: Also, we cannot be certain the transporter will operate under those conditions. If a man is beaming up when that hits, we may lose him.
KIRK: That's exactly why I've decided to set the trap myself.
SPOCK: Captain, there is so little hemoglobin in my green blood, the creature could not harm me extensively. It therefore seems logical for me to be the one
KIRK: Negative, Mister Spock. In case this plan fails, I'll need you aboard the ship. In that event, we'll need another plan.
SPOCK: It will require two men to transport the antimatter unit.
GARROVICK: I'd like permission to go with you, sir.
KIRK: I had you in mind, Mister Garrovick.

[Planet surface]

(Kirk, Garrovick and a blue ball under a floating carrying device beam down.)
KIRK: Kirk to Enterprise.
SPOCK [OC]: Spock here, Captain.
KIRK: Proceed immediately to maximum orbit.
SPOCK [OC]: Acknowledged.
GARROVICK: Just think, Captain, less than one ounce of antimatter here is more powerful than ten thousand cobalt bombs.
KIRK: Let's hope it's as powerful as man will ever get. Detonator.
GARROVICK: Aye, sir.
(He primes and sets it on the anti-grav unit.)
KIRK: Kirk to Enterprise.

[Bridge]

SPOCK: Spock here, Captain. Holding at thirty thousand kilometres.

[Planet surface]

KIRK: Antimatter container positioned and armed. I'll call you back when it's baited. Kirk out.
GARROVICK: Captain, look!
(The cloud is already over the bottle of blood. Within moments it is empty.)
GARROVICK: The haemoplasm. The bait's already taken.
KIRK: We'll need something else for bait.
GARROVICK: Sir, that thing only feeds on blood.
KIRK: Garrovick, get back to the ship. Tell them to prepare to detonate.
GARROVICK: Captain, you're not going to be the bait.
KIRK: I said, get back to the ship. Ensign, I gave you an order.
GARROVICK: Yes, sir.
(A quick karate chop knocks Kirk down but not out. He lands a couple of punches on Garrovick.)
KIRK: Consider yourself on report. This is no time for heroics. I have no intention of sacrificing myself, at least not yet. (into communicator) Spock? Spock?
SPOCK [OC]: Spock here.
KIRK: Scan us and lock on to us. It's going to be close. Very, very close. Stand by. Stand by, Enterprise.
(The cloud approaches.)
GARROVICK: I can smell it, Captain. It's sickening. Honey sweet.
KIRK: Stand by, Enterprise. (The cloud reaches them) Now! Energise and detonate!
(BANG!)

[Transporter room]

(Spock and Scott are at the controls with McCoy watching.)
SPOCK: Reset. Energise.
CHEKOV [OC]: All decks, stand by. Shock waves.
(The ship is shaken, and still nothing appears on the transporter pad.)
MCCOY: Do something.
SPOCK: We are, Doctor. Cross-circuiting to A.
SCOTT: Got them. A piece of them, anyway.
SPOCK: Cross-circuiting to B.
MCCOY: Crazy way to travel, spreading a man's molecules all over the universe.
(Finally the swirly bits solidify into two men.)
SCOTT: Captain, thank heaven.
SPOCK: Mister Scott, there was no deity involved. It was my cross-circuiting to B that recovered them.
MCCOY: Well then, thank pitchforks and pointed ears. As long as it worked, Jim.
KIRK: That's a fair statement, Bones. Now that the creature is dead, let's save some lives. We'll deliver your medicine. Bridge, this is Kirk.
UHURA [OC]: Uhura here.
KIRK: Have Mister Chekov lay in a course for a rendezvous with the Yorktown, maximum warp.
UHURA [OC]: Aye, sir.
KIRK: Oh, Ensign, meet me in my quarters when you've cleaned up. I'd like to talk to you about your father. Several tall stories I think you'd like to hear.
GARROVICK: Thank you, sir. I would.