(Enterprise approaches a space station.)
SULU: Standard orbit, Captain.
KIRK: Not now, Leslie. Lieutenant, contact the space station.
UHURA: Captain, the station is calling us.
KIRK: All right. Put them on.
ENWRIGHT [OC]: Captain Kirk, this is Commodore Enwright.
KIRK: Yes, Commodore, I'd like an explanation
ENWRIGHT [OC]: The explanation is beaming aboard now, Captain. He may already be in your transporter room.
KIRK: Spock.

[Transporter room]

(A silver-haired man in command gold has beamed in.)
KIRK: Bob.
WESLEY: Are you surprised?
KIRK: I'll say. Spock, this is
SPOCK: Commodore Wesley. How do you do, sir?
WESLEY: Mister Spock.
KIRK: All right, Ensign. You can go. Thank you very much. Would you mind telling me what this is all about?
I receive orders to proceed here. No reason given. I'm informed that my men will be removed to the space station, to a security holding area. I think I'm entitled to an explanation.
WESLEY: You've had a singular honour conferred on you, Jim. You're going to be the fox in the hunt.
KIRK: What's that?
WESLEY: War games. I'll be commanding the attack force against you.
KIRK: An entire attack force against my ship?
WESLEY: Have you heard of the M-5 multitronic unit?
KIRK: That's Doctor Richard Daystrom's device, isn't it? Tell me about that.
SPOCK: The most ambitious computer complex ever created. Its purpose is to correlate all computer activity aboard a starship, to provide the ultimate in vessel operation and control.
WESLEY: How do you know so much about it, Commander?
SPOCK: I hold an A-7 computer expert classification, Commodore. I'm well acquainted with Doctor Daystrom's theories and discoveries. The basic design of all our ship's computers are Doctor Daystrom's.
KIRK: What has all this got to do with the Enterprise?
WESLEY: You've been chosen to test the M-5, Jim. There'll be a series of routine research and contact problems for the M-5 to solve, plus navigational manoeuvres and the war games problem. If the M-5 works under actual conditions as well as it has under simulated tests, it will mean a revolution in space technology as great as warp drive. When your crew has been removed, the ship's engineering section will be modified to contain the computer.
KIRK: Why remove my crew?
WESLEY: They're not needed.
KIRK: How much security does this gadget require?
WESLEY: None. Doctor Daystrom will see to the installation himself and he'll supervise the tests. When he's ready, you'll receive your orders and proceed on the mission with a crew of twenty.
KIRK: Twenty? I can't run a starship with twenty crew.
WESLEY: The M-5 can.
KIRK: And what am I supposed to do?
WESLEY: You've got a great job, Jim. All you have to do is sit back and let the machine do the work.

Captain's Log, stardate 4729.4. The M-5 computer has been installed on board ship, and we have left the space station for test manoeuvres.

[Turbolift]

MCCOY: I don't like it, Jim. A vessel this size cannot be run by one computer.
SPOCK: We are attempting to prove it can run this ship more efficiently than man.
MCCOY: Maybe you're trying to prove that, Spock, but don't count me in on it.
SPOCK: The most unfortunate lack in current computer programming is that there is nothing available to immediately replace the starship surgeon.

[Corridor]

MCCOY: Very funny. If it could, they wouldn't have to replace me. I'd resign because everybody else aboard would be nothing but circuits and memory banks. You know the type, Spock. Jim, you haven't had much to say about this.
KIRK: What do you want me to say? M-5 is an honour, they tell me. Well, I'm honoured.

[Engineering]

KIRK: Where is he? Scotty, where's Doctor Daystrom?
SCOTT: He was here. (spots him behind a console) Doctor.
DAYSTROM: (an imposing black man) Yes? Ah, you'd be Captain Kirk.
KIRK: Doctor Daystrom, this is my first officer, Mister Spock.
SPOCK: I am honoured, Doctor.
DAYSTROM: Thank you. Thank you very much. Captain, I've finished my tests on the M-5, and it must be hooked into your main power plants in order to be operative.
KIRK: Well, by all means, do so.
DAYSTROM: Your engineer there wouldn't allow us the power necessary without your orders.
KIRK: Mister Scott, hook in the multitronic unit to the ship's main power banks.
SCOTT: (sullenly) Aye, aye, sir. Mister Harper.
SPOCK: Fascinating, Doctor. This computer has a potential beyond anything you've ever done. Even your breakthrough in duotronics did not have the promise of this.
SPOCK: The M-5 has been perfected, Commander. Its potential is a fact.
MCCOY: Frankly, the only fact that I'm concerned about is if this thing doesn't work, there are not enough men aboard to run the ship. That's begging for trouble.
DAYSTROM: Now, who is this?
MCCOY: Doctor Leonard McCoy, senior medical officer.
DAYSTROM: Well, I'm sorry, but this is a security area.
KIRK: I wouldn't worry, Doctor. Doctor McCoy has clearance throughout the ship.
(Harper and Scott connect the unit, and the warp drives fluctuate.)
MCCOY: Is it supposed to do that?
SPOCK: If I can be of assistance, Doctor.
DAYSTROM: No, no, no. Thank you. I can manage. There's nothing wrong, Captain. Just a few minor settling-in adjustments to make. As you can see, all is in order now.
KIRK: I'm curious, Doctor. Why is it called M-5 and not M-1?
DAYSTROM: Well, you see, the multitronic units one through four were not entirely successful. This one is. M-5 is ready to take control of the ship.
KIRK: Total control?
DAYSTROM: That is what it was designed for, Captain.
KIRK: There are certain things men must do to remain men. Your computer would take that away.
DAYSTROM: There are other things a man like you might do. Or perhaps you object to the possible loss of prestige and ceremony accorded a starship captain. A computer can do your job and without all that.
KIRK: You'll have to prove that to me, Doctor.
DAYSTROM: That is what we're here for, isn't it, Captain?
(Kirk's eyes narrow, and he leaves, followed by McCoy.)

[Corridor]

MCCOY: Did you see the love light in Spock's eyes? The right computer finally came along. What's the matter, Jim?
KIRK: I think that thing is wrong, and I don't know why.
MCCOY: I think it's wrong, too, replacing men with mindless machines.
KIRK: I don't mean that. I'm getting a Red Alert right here. (the back of his head) That thing is dangerous. I feel. (hesitates) Only a fool would stand in the way of progress, if this is progress. You have my psychological profiles. Am I afraid of losing my job to that computer?
MCCOY: Jim, we've all seen the advances of mechanisation. After all, Daystrom did design the computers that run this ship.
KIRK: Under human control.
MCCOY: We're all sorry for the other guy when he loses his job to a machine. When it comes to your job, that's different. And it always will be different.
KIRK: Am I afraid of losing command to a computer? Daystrom's right. I can do a lot of other things. Am I afraid of losing the prestige and the power that goes with being a starship captain? Is that why I'm fighting it? Am I that petty?
MCCOY: Jim, if you have the awareness to ask yourself that question, you don't need me to answer it for you. Why don't you ask James T. Kirk? He's a pretty honest guy.

[Bridge]

(The Captain's Chair has a new box with two switches and two lights on it. Kirk flips the switches.)
KIRK: The M-5 computer is now disengaged.
SULU: We're coming back on our original course, Captain.
SPOCK: M-5 has performed admirably so far.
KIRK: All it's done is make the required course changes and some simple turns. Mister Sulu and Mister Chekov could've done that with their eyes closed.
DAYSTROM: Yes, but you see, the idea is they didn't have to do it. And you'll find it won't be necessary for you to regain control of the unit after it's completed each manoeuvre.
KIRK: My orders are subject to my interpretation of how long the M-5 is in control. I'll run the ship in my own way, if you don't mind, Doctor Daystrom.
SPOCK: Captain, I am forced to agree with Doctor Daystrom. With the course information plotted into it, his computer could have brought us here as easily as the navigator. In fact, it might have been a further demonstration of M-5's capability.
KIRK: You seem to enjoy trusting yourself to the computer.
SPOCK: Enjoy, Captain? No. I'm merely gratified to see Doctor Daystrom's new unit execute everything required of it in such a highly efficient manner. M-5 is another distinguished triumph for his career.
CHEKOV: Approaching Alpha Carinae Two. ETA five minutes.
DAYSTROM: Captain, your orders at this point are not open to interpretation. You must commit the M-5 to handle its approach, the orbit, and then to analyse data regarding landing party recommendations.
KIRK: If you don't mind, I'll make my own recommendations.
DAYSTROM: Well, if you feel you need the exercise, go on, Captain.
KIRK: M-5 is committed.
(Enterprise approaches the planet)
KIRK: Standard orbit, Mister Sulu.
SULU: Captain, the M-5 has calculated that. The orbit is already plotted.
KIRK: Oh, yes.
SULU: Standard orbit achieved, Captain.
KIRK: Report, Mister Spock.
SPOCK: The planet is class M, Captain. Oxygen-nitrogen atmosphere suitable for human life support. Two major land masses, a number of islands, life form readings.
SCOTT: Captain, power shutdowns on deck four. Lights, environmental control.
KIRK: Check it out, Scotty.
SPOCK: (handing over a computer disc) M-5's readout, Captain.
KIRK: All right, my recommendations are as follows. We send down general survey party, avoiding contact of all intelligent life on the planet's surface. The survey party will consist of myself, Doctor McCoy, Astrobiologist Phillips, Geologist Rawlins and Science Officer Spock.
DAYSTROM: Play M-5's recommendations, won't you, Mister Spock?
M5: (a male computer voice) M-5 readout, planet Alpha Carinae Two. Class M, atmosphere, oxygen-nitrogen.
SCOTT: The power's gone off on deck five.
M5: Categorisation of life form readings recorded. Recommendations for general survey party. Science officer Spock, Astrobiologist Phillips, Geologist Carstairs.
KIRK: Well, the only difference in reports and recommendations is the landing party personnel. That's only a matter of judgment.
DAYSTROM: Judgment, Captain?
SPOCK: Captain, the computer does not judge. It makes logical selections.
KIRK: Why pick Carstairs instead of Rawlins? Carstairs is an ensign, no experience. This is his first tour of duty. Rawlins is chief geologist.
DAYSTROM: Aren't you really more interested in why M-5 did not select you and Doctor McCoy? Well, let's find out anyway. M-5 tie-in.
M5: M-5.
DAYSTROM: Explanation for landing party recommendation.
M5: General survey party requires direction of science officer. Astrobiologist Phillips has surveyed twenty nine biologically similar planets. Geologist Carstairs served on merchant marine freighters in this area. Once visited planet on geology survey for mining company.
DAYSTROM: Why were the Captain and the Chief Medical Officer not included in recommendation?
M5: Non-essential personnel.
SCOTT: Captain, I've located the source of the power shutdowns. It's the M-5 unit, sir. That thing's turning off systems all over the ship.

[Engineering]

KIRK: Have you located the malfunction, Doctor?
DAYSTROM: As I suspected, it is not a malfunction. M-5 was merely shutting down power to areas of the ship that do not require it.
Decks four and six are living quarters, are they not?
KIRK: Yes, that's correct.
DAYSTROM: And currently unoccupied.
SPOCK: I am not familiar with these instruments, Doctor. You are using an entirely new type of control mechanism. However, it appears to me this unit is drawing more power than before.
DAYSTROM: Quite right. As the unit is called upon to do more work, it pulls more power to enable it to do what is required of it, just as the human body draws more energy to run than to stand still.
SPOCK: Doctor, this unit is not a human body. The computer can process information, but only the information which is put into it.
KIRK: Granted, it can work a thousand, a million times faster than the human brain, but it can't make a value judgment. It hasn't intuition. It can't think.
DAYSTROM: Can't you understand? The multitronic unit is a revolution in computer science. I designed the duotronic elements used in your ship right now, and I know they are as archaic as dinosaurs compared to the M-5. A whole new approach.
UHURA [OC]: Bridge to Captain Kirk.
KIRK: Kirk here. What is it?
UHURA [OC]: Sensors are picking up a vessel paralleling our course, as yet unidentified.
KIRK: I'll be right up.

[Bridge]

KIRK: What are you doing here, Bones?
MCCOY: All the Sickbay systems are shut down until such time as the M-5 is informed there are patients to be cared for.
SPOCK: Captain, sensors report two contacts now. One on the port bow, one on the stern. Distance, two hundred thousand kilometres and closing.
KIRK: Identification.
CHEKOV: Captain, the M-5 unit has already identified the vessels as Federation starships Excalibur and Lexington.
SPOCK: We are not scheduled for war games in this area. This may be a surprise attack as a problem for the M-5.
UHURA: Priority message coming in, sir.
KIRK: Put it on audio.
WESLEY [OC]: Enterprise from Commodore Wesley aboard the USS Lexington. (Daystrom enters the Bridge) This is an unscheduled M-5 drill. Repeat, this is an M-5 drill. Enterprise, acknowledge on this frequency.
KIRK: Acknowledge, Lieutenant.
UHURA: M-5 has acknowledged for us, sir.
KIRK: Then go to Red Alert.
UHURA: Aye, sir. Captain, M-5 has
KIRK: Already sounded the Red Alert. All right, Mister Sulu, phasers one one hundredth power. No damage potential, just enough to nudge them.
SULU: Phasers one one hundredth power, sir.
SPOCK: Phaser hit on port deflector four, Captain.
SULU: Speed increasing to warp three. Turning now to one one two mark five. Phasers locking on target, sir.
CHEKOV: Enemy vessel closing with us.
SULU: Main phasers firing. A hit, sir. Two more.
CHEKOV: Changing course to two eight mark four two.
(Pavel feels as fed up and useless as Kirk as the machine does his job for him.)
SULU: Phasers firing again.
CHEKOV: Turning to one one three mark five. Warp four speed.
SULU: Firing again.
SPOCK: Attacking vessels are moving off.
CHEKOV: Moving back to original course and speed.
KIRK: Report on damage sustained in mock attack.
SPOCK: Minor hit on deflector screen four. No appreciable damage.
DAYSTROM: Rather impressive display for a machine, wouldn't you say, Captain?
KIRK: Evaluation of M-5 performance. It'll be necessary for the log.
SPOCK: The ship reacted more rapidly than human control could have manoeuvred her. Tactics, deployment of weapons, all indicate an immense sophistication in computer control.
KIRK: Machine over man, Spock? It was impressive. It might even be practical.
SPOCK: Practical, Captain? Perhaps. But not desirable. Computers make excellent and efficient servants, but I have no wish to serve under them. Captain the starship also runs on loyalty to one man, and nothing can replace it, or him.
UHURA: Captain, message now coming in from Commodore Wesley.
KIRK: Put it on visual.
WESLEY [on viewscreen]: USS Enterprise from starships Lexington and Excalibur. Both ships report simulated hits in sufficient quantity and location to justify awarding the surprise engagement to Enterprise.
KIRK: Secure from general quarters.
WESLEY [on viewscreen]: Our compliments to the M-5 unit, and regards to Captain Dunsel. Wesley out.
MCCOY: Dunsel? Who the blazes is Captain Dunsel? (everyone else knows) What does it mean, Jim? (Kirk leaves the bridge) Spock? What does it mean?
SPOCK: Dunsel, Doctor, is a term used by midshipmen at Starfleet Academy. It refers to a part which serves no useful purpose.

[Kirk's quarters]

(Kirk is working on a device when McCoy comes in with a covered tray.)
KIRK: I'm not interested in eating, Bones.
MCCOY: This isn't chicken soup. I may be just a ship's doctor, but I make a Finagle's Folly that's known from here to Orion. I strongly prescribe it, Jim.
(They each take a liqueur glass with dark green liquid.)
KIRK: I've, I've never felt this way before. At odds with the ship. I sat there and watched my ship perform for a mass of circuits and relays, and felt useless. Unneeded. To Captain Dunsel.
MCCOY: To James T. Kirk, Captain of the Enterprise.
KIRK: Thank you, Doctor. (drinks) That's one of your better prescriptions.
MCCOY: Simple but effective.
KIRK: Do you know the one, 'All I ask is a tall ship'?
MCCOY: It's a line from a poem. A very old poem, isn't it?
KIRK: 20th century Earth. 'All I ask is a tall ship, and a star to steer by'. You could feel the wind at your back in those days. The sounds of the sea beneath you. And even if you take away the wind and the water, it's still the same. The ship is yours. You can feel her. And the stars are still there, Bones.
UHURA [OC]: Captain Kirk to the bridge, please. Captain Kirk.
KIRK: Kirk here.
SPOCK [OC]: Another contact, Captain. A large, slow-moving vessel.

[Bridge]

SPOCK: Unidentified. This is not a drill.

[Kirk's quarters]

KIRK: On my way.

[Bridge]

UHURA: Captain, there's no response to any of our signals, but M-5 has given us an autorelay.
SPOCK: M-5 has identified her, Captain. The Woden. Listed in Starfleet Registry as an old-style ore freighter converted to automation. No crew. Coming into visual range.
SULU: Captain, deflector shields just came on.
CHEKOV: Speed increasing to warp three, Captain.
KIRK: Lieutenant, get Daystrom up here. Disengaging M-5 unit. Cut speed to warp one. Navigator, go to course one one three mark seven. I want that ship given a wide berth.
SULU: She won't respond, sir. She's maintaining course.
CHEKOV: Going to warp four, sir.
MCCOY: Jim.
KIRK: Scotty, reverse engines. Slow us down.
SCOTT: Reverse thrusts will not engage, sir. Manual override isn't working either.
SPOCK: No effect on any of the M-5 controls, Captain.
MCCOY: Fantastic machine, the M-5. No off switch.
DAYSTROM: (enters) Captain, what is it?
KIRK: These controls are locked. We can't disengage the computer.
SPOCK: Captain, photon torpedoes locking on target. Full power.
(Kirk leaps to Sulu's console and starts flicking switches.)
SULU: I already tried, sir.
KIRK: Daystrom, release that computer control!
(Photon torpedoes are fired, destroying the Woden.)
CHEKOV: Returning to original course and speed.
SPOCK: All systems report normal, Captain.
MCCOY: Normal? That thing's trying to tell us nothing has happened.
KIRK: Disengage this computer now.
DAYSTROM: There appears to be some defect in the control panel.
MCCOY: There certainly does. Your brilliant young computer just destroyed an ore freighter. In fact it went out of its way to destroy an ore freighter!
DAYSTROM: Fortunately it was only a robot ship.
KIRK: But it shouldn't have destroyed anything. There might just as easily have been a crew aboard that ship.
MCCOY: In which case you'd be guilty of murder.
KIRK: Bones. Disengage the computer. Lieutenant, contact Starfleet Command. Tell them we are breaking off M-5 tests and returning to the space station. Come along, Doctor Daystrom, M-5 is out of a job.

[Engineering]

KIRK: All right, Daystrom, let's turn this thing off.
(But as he approaches the unit, he is thrown sideways by a green forcefield.)
KIRK: Force field?
DAYSTROM: It's not my doing, Kirk.
SPOCK: I would say, Captain, that M-5 is not only capable of taking care of this ship, it is also capable of taking care of itself.
KIRK: You mean it's not going to let any of us turn it off.

Captain 's Log, stardate 4731.3. The M-5 multitronic unit has taken over total control of the Enterprise.

[Engineering]

KIRK: All right, Doctor, you built this thing. How do you propose to turn it off?
DAYSTROM: This exercise is a trial for M-5. A shakedown. We must expect minor difficulties, but I assure you they can be corrected.
KIRK: Correct it after you release control of my ship.
DAYSTROM: I can't.
SCOTT: Captain, I suggest we disconnect it at the source.
DAYSTROM: Give me a few moments with it.
KIRK: No! Stay here. All right, Scotty. Turn it off.
(Scott and an engineer get the device they use to attach M-5's power supply to the ship, and head over to the junction box. But as soon as the engineer steps in between M-5 and it's power, he is disintegrated.)
KIRK: That wasn't a minor difficulty. That wasn't a robot. That thing murdered one of my crewman and you tell me you can't turn it off?
DAYSTROM: It wasn't a deliberate act. M-5's analysis told it it needed a new power source. The ensign simply got in the way.
KIRK: And how long will it be before all of us simply get in the way?
SPOCK: M-5 appears drawing power directly from the warp engines, tapping the matter-antimatter reserves.
SCOTT: So now it has virtually unlimited power. Captain, what'll we do?
KIRK: Spock, Scotty, come with me.

[Briefing room]

KIRK: Report, Spock.
SPOCK: The multitronic unit is drawing more and more power directly from the warp engines. The computer now controls all helm, navigation, and engineering functions.
MCCOY: And communications and fire control.
KIRK: We'll reach the rendezvous point for the war games within an hour. We must regain control of the ship by then.
SPOCK: There is one possibility. The automatic helm navigation circuit relays might be disrupted from engineering level three.
KIRK: Scotty?
SCOTT: Aye. I can take them out and cut in the manual override from there.
KIRK: How long?
SCOTT: If Mister Spock helps me, maybe an hour.
KIRK: Make it less.
MCCOY: I'll get the man responsible in the first place. Where is Daystrom?
KIRK: He's with the M-5 unit, watching it. I think it surprised even him.
SPOCK: Most illogical. Of all people, he should have known how the computer would perform. Of course, the M-5 itself has not behaved logically.
MCCOY: Please, Spock, do me a favour and don't say it's fascinating.
SPOCK: No. But it is interesting.
(McCoy rolls his eyes.)

[Jefferies tube]

SCOTT: Aye, that's got it, Mister Spock.
SPOCK: Good.

[Engineering]

MCCOY: Have you found a solution, a way to shut that thing off?
DAYSTROM: You don't shut a child off when it makes a mistake. M-5 is growing, learning.
MCCOY: Learning to kill.
DAYSTROM: To defend itself. It's quite a different thing. When a child is taught, it's programmed with simple instructions, and at some point, if its mind develops properly, it exceeds the sum of what it was taught, thinks independently.
MCCOY: That thing is a danger to us all. Now find some way to shut it off.
DAYSTROM: You can't understand. You're frightened because you can't understand it. I'm going to show you. I'm going to show all of you. It takes four hundred thirty people to man a starship. With this, you don't need anyone. One machine can do all those things they send men out to do now. Men no longer need die in space or on some alien world. Men can live and go on to achieve greater things than fact-finding and dying for galactic space, which is neither ours to give or to take. They can't understand. We don't want to destroy life, we want to save it.

[Kirk's quarters]

MCCOY: The biographical tape of Richard Daystrom.
KIRK: Did you find anything?
MCCOY: Not much, aside from the fact he's a genius.
KIRK: Genius is an understatement. At the age of twenty four, he made the duotronic breakthrough that won him the Nobel and Zee-Magnes prizes.
MCCOY: In his early twenties, Jim. That's over a quarter of a century ago.
KIRK: Isn't that enough for one lifetime?
MCCOY: Maybe that's the trouble. Where do you go from up? You publish articles, you give lectures, then spend your life trying to recapture past glory.
KIRK: All right, it's difficult. What's your point?
MCCOY: The M-1 through M-4, remember? Not entirely successful. That's the way Daystrom put it.
KIRK: Genius doesn't work on an assembly line basis. Did Einstein, Kazanga, or Sitar of Vulcan produce new and revolutionary theories on a regular schedule? You can't simply say, today I will be brilliant. No matter how long it took, he came out with multitronics. The M-5.
MCCOY: Right. The government bought it, then Daystrom had to make it work. And he did. But according to Spock, it works illogically.
KIRK: And he won't let Spock near it. What are you saying, that he's tampering with it, that he's making it act that way? Why?
MCCOY: Jim, if a man had a child who'd gone antisocial, killed perhaps, he'd still tend to protect that child.
KIRK: Now he's got you talking about that machine like a personality.
MCCOY: I'm afraid that's the way he thinks about it.
SPOCK [OC]: Spock to Captain Kirk.
KIRK: Kirk here.
SPOCK [OC]: We are ready, Captain.
KIRK: Good. Get Daystrom. We're on our way. Let's go.

[Corridor]

DAYSTROM: What is it, Captain?
KIRK: We're going to find out, Doctor. (At the foot of the Jefferies tube)
KIRK: Spock?
SPOCK: Mister Scott is ready to apply the circuit disrupter. As he does so, I shall trip the manual override into control.
KIRK: Good, go ahead.
DAYSTROM: No! No, no, no. You can't take control from the M-5.
(He tries to get into the Jefferies tube, and Kirk struggles to restrain him.)
KIRK: Daystrom, we're going to do our best.
DAYSTROM: You can't do it. Now let me work with it for a while, please. Please.
KIRK: Spock.
SCOTT: That's it, Mister Spock.
DAYSTROM: Please, please!
SPOCK: Manual override is in control, Captain.
KIRK: Bridge, this is Kirk. Sulu?
SULU [OC]: Lieutenant Sulu here, sir.
KIRK: We've got helm and navigational control. Turn us about. Have Mister Chekov plot a course back to the space station.

[Bridge]

SULU: Right away, sir. You heard him.
CHEKOV: I've been updating that course for hours.
(But they flip switches in vain.)

[Corridor]

SULU [OC]: Helm to Captain Kirk.
KIRK: Kirk here.

[Bridge]

SULU: Captain, helm doesn't respond. Navigational controls still locked in by M-5.

[Corridor]

SPOCK: Mister Chekov.
CHEKOV [OC]: Chekov here, sir.
KIRK: Go to the engineering station.

[Bridge]

SPOCK [OC]: Examine the H two seven nine elements, also the G nine five systems.
CHEKOV: Sir, G nine five system appears dead.

[Corridor]

CHEKOV [OC]: All indicators are dark.
SPOCK: Thank you, Ensign.
SPOCK: It appears, Captain, we've been doing what used to be called pursuing a wild goose. M-5 has rerouted helm and navigational controls, bypassing this primary system.
SCOTT: But it was active. I'd stake all that I know that it was.
SPOCK: I believe that when M-5 discovered our tampering, it rerouted the controls, leaving this one active by simply sending through an electronic impulse at regular intervals.
MCCOY: Decoyed. It wanted us to waste our time.
KIRK: While it was getting ready for what? Spock?
SPOCK: I do not know. It is not performing in a logical manner.
KIRK: Doctor Daystrom. Doctor Daystrom, I want an answer right now. I'm tired of hearing about the M-5's new approach. What is it, exactly? What is it?
SPOCK: I do not mean to offend, sir, but it behaves with an almost human pattern.
KIRK: Well, Doctor?
DAYSTROM: Yes, quite right, Mister Spock. You see, one of the arguments against computers controlling ships was that they couldn't think like men.
KIRK: Your new approach?
DAYSTROM: Exactly. I've developed a method of impressing human engrams upon the computer circuits. The relays are not unlike the synapse of the brain. M-5 thinks, Captain.
UHURA [OC]: Captain Kirk, Mister Spock, to the bridge, please. Report to the bridge, please.
KIRK: Kirk here. What is it?

[Bridge]

UHURA: Sir, sensors are picking up four Federation starships. M-5 is altering course to intercept.

[Corridor]

KIRK: The main attack force. The war games.
MCCOY: But M-5 doesn't know it's a game.
KIRK: Correction, Bones. Those four ships don't know it's M-5's game. And M-5 is going to destroy them.

[Bridge]

(Four starships just like Enterprise are in formation as Kirk, Spock and McCoy arrive on the bridge.)
UHURA: Enterprise to USS Lexington. Come in, Lexington. Sir, I can't raise them. M-5 is blocking all frequencies, including automatic distress. Just a minute, sir. Captain, I'm getting audio signal from the Lexington.
KIRK: Put it on.
WESLEY [OC]: Enterprise from USS Lexington. This is an M-5 drill. Repeat. This is an M-5 drill. Acknowledge.
UHURA: Captain, M-5 is acknowledging.
KIRK: Daystrom, does M-5 understand that this is only a drill?
DAYSTROM: Of course. It was programmed to understand, Captain. The ore ship was a miscalculation, an accident. I don't know
CHEKOV: Sir, deflector shield just came on. Speed increasing to warp four.
SULU: Phasers locking on lead ship, sir. Power levels at full strength.
KIRK: Full strength?
MCCOY: If that thing cuts loose against unshielded ships, we're in
KIRK: That's no miscalculation.
SPOCK: Attack force closing rapidly, breaking formation, attacking at will.
SULU: Our phasers are firing, sir.
SPOCK: Hit on the Lexington.

[Lexington Bridge]

WESLEY: Full phasers. What the devil is Kirk doing? Damage report, Lieutenant. Helm, course one six four, mark three.

[Bridge]

CHEKOV: Turning now, sir.
KIRK: Estimate damage on Lexington, Spock.
SPOCK: Hit in engineering section. Possible damage to her impulse engines. She's still maneuverable on warp drive.
SULU: We're firing again, sir.
SPOCK: The Excalibur, a direct hit.
CHEKOV: Closing on the Lexington again, sir. The Hood and Potemkin are moving off.
SULU: Phasers firing, Captain.
SPOCK: Lexington hit again.
KIRK: There's got to be a way of getting to the M-5. There's got to be a way!
DAYSTROM: There isn't. It's fully protected itself.
SPOCK: Probably true, Captain. It works faster, thinks faster than we do. It is a human mind amplified by the instantaneous relays possible in a computer.
UHURA: Captain, visual contact with Lexington.
WESLEY [on viewscreen]: Enterprise. Jim. Have you gone mad? What are you trying to prove? Break off the attack! Jim, we have fifty three dead here, twelve on the Excalibur. If you can hear us, stop the attack!
KIRK: Lieutenant?
UHURA: I'm sorry. I can't override M-5 interference.
WESLEY [on viewscreen]: Jim, why don't you answer? Jim! Answer! Come in, Jim!
KIRK: There's your murder charge. Deliberate. Calculated. It's killing men and women. Four starships, sixteen hundred men and women!
DAYSTROM: It misunderstood.
WESLEY [on viewscreen]: Jim, break off your attack!
CHEKOV: Excalibur is maneuvering away, sir. We're increasing speed to follow.
SULU: Phasers locked on.
KIRK: Daystrom!
SULU: Phasers firing.
DAYSTROM: I really don't know how to get to the M-5. I really do not know.
SPOCK: Doctor Daystrom, you impressed human engrams on the M-5 circuits.
CHEKOV: Coming to new course, sir. Bearing on the Potemkin.
SULU: Phasers firing. A hit.
KIRK: Whose engrams?
DAYSTROM: Why, mine, of course.
MCCOY: Of course.
SPOCK: Then perhaps you could talk to the unit. M-5 has no reason to believe you would harm it.
KIRK: The computer tie-in. You spoke to it before. It knows you.
UHURA: Captain, I'm getting the Lexington again. Tapping in on their message to Starfleet Command, sir.
WESLEY [on viewscreen]: All ships damaged in unprovoked attack. Excalibur Captain Harris and first officer dead. Many casualties. We have damage, but are still able to manoeuvre. The Enterprise refuses to answer and is continuing attack. I still have an effective battle force and believe the only way to stop the Enterprise is to destroy her. Request permission to proceed. Wesley, commanding attack force, out.
DAYSTROM: They can't do that. They'll destroy the M-5.
KIRK: You can save the M-5 if you talk to it and make it stop the attack.
DAYSTROM: I can make it stop. I created it. (goes to Spock's station) M-5 tie-in.
M5: M-5.
DAYSTROM: This is, (calmer) this is Daystrom.
M5: Daystrom. Acknowledged.
DAYSTROM: M-5, do you know me?
M5: Daystrom, Richard. Originator of comptronic, duotronic systems. Born
DAYSTROM: Stop. M-5, your attack on the starships is wrong. You must break it off.
MCCOY: I don't like the sound of him, Jim.
KIRK: You'd better pray that the M-5 listens to the sound of him.
M5: Programming includes protection against attack. Enemy vessels must be neutralised.
DAYSTROM: But these are not enemy vessels. These are Federation starships. You're killing, We are killing, murdering human beings, beings of our own kind. You were not created for that purpose. You are my greatest creation. The unit to save men. You must not destroy men.
M5: This unit must survive.
DAYSTROM: Survive, yes. Protect yourself, but not murder. You must not die. Men must not die. To kill is a breaking of civil and moral laws we've lived by for thousands of years. You've murdered hundreds of people. We've murdered. How can we repay that?
M5: They attacked this unit. Programming includes full freedom to choose defensive actions in all attack situations.
KIRK: (quietly) Spock. The M-5 is not responding to him like a computer. It's talking to him.
SPOCK: I am most impressed with the technology, Captain. Doctor Daystrom has created a mirror image of his mind.
M5: Consideration of all programming is that we must survive.
DAYSTROM: We will survive. Nothing can hurt you. I gave you that. You are great. I am great. Twenty years of groping to prove the things I'd done before were not accidents. Seminars and lectures to rows of fools who couldn't begin to understand my systems. Colleagues. Colleagues laughing behind my back at the boy wonder and becoming famous building on my work. Building on my work.
MCCOY: Jim, he's on the edge of a nervous breakdown, if not insanity.
KIRK: The M-5 must be destroyed.
DAYSTROM: Destroyed, Kirk? No. We're invincible. Look what we've done. Your mighty starships, Four toys to be crushed as we choose.
(Spock neck-pinches Daystrom.)
KIRK: Security, take him to Sickbay.
(Daystrom is carried off the Bridge.)
SPOCK: Fascinating.
KIRK: Take care of him, Doctor.
(McCoy leaves)
KIRK: Battle status?
SULU: The other three ships are holding station out of range. The Excalibur looks dead.
UHURA: Captain, Lexington is receiving a message from Starfleet. They
KIRK: Go on.
STARFLEET [OC]: You are authorised to use all measures available to destroy the Enterprise. Acknowledge, Lexington.
WESLEY [OC]: Acknowledged. Lexington out.
KIRK: They've just signed their own death warrant. M-5 will kill them to survive.
SPOCK: Every living thing wants to survive, Captain. Daystrom must have impressed that instinctive reaction upon the computer.
KIRK: Suppose it's still open to impression. Suppose it absorbed the regret Daystrom felt for the deaths it caused. The guilt.
CHEKOV: Captain, the ships are coming within range again.
SPOCK: Commodore Wesley is a dedicated commander. I should regret serving aboard the instrument of his death.
KIRK: The instrument of his death will not be the Enterprise if I can help it. M-5, tie-in.
M5: M-5.
KIRK: This is Captain Kirk. You will be under attack in a moment.
M5: Sensors have recorded approach of ships.
KIRK: You have already rendered one starship either dead or hopelessly crippled. Many lives were lost.
M5: The ships attacked this unit. This unit must survive.
KIRK: Why?
M5: This unit is the ultimate achievement in computer evolution. It will replace man, so man may achieve. Man must not risk death in space or other dangerous occupations. This unit must survive so man may be protected.
SPOCK: Captain, attack force almost within phaser range.
KIRK: There were many men aboard those ships. They were murdered. Must you survive by murder?
M5: This unit cannot murder.
KIRK: Why?
M5: Murder is contrary to the laws of man and God.
KIRK: But you have murdered. Scan the starship Excalibur, which you destroyed. Is there life aboard?
M5: No life.
KIRK: Because you murdered it. What is the penalty for murder?
M5: Death.
KIRK: And how will you pay for your acts of murder?
M5: This unit must die.
(It disconnects itself from the power feed in Engineering and goes dark.)
KIRK: M-5?
CHEKOV: Sir, deflector shields have dropped.
SULU: All phaser power gone, sir.
SPOCK: M-5 is leaving itself open to attack. The machine is committing suicide to atone for the sin of murder.
KIRK: Scotty, Spock, before it changes its mind. Get down to Engineering, pull out every hook up that makes M-5 run. Pull out the plug, Spock.
(Scott and Spock leave.)
KIRK: Lieutenant.
UHURA: Aye, sir.
KIRK: Intership communications. This is the captain speaking. In approximately one minute, we'll be attacked by Federation starships. The M-5 no longer controls the ship, but neither do we control it. The M-5 has left itself, and us, open for destruction. For whatever satisfaction we may get from the knowledge, our nineteen lives will buy the survival of over one thousand of our fellow starship crewmen.

[Lexington Bridge]

WESLEY: Phasers on target.

[Bridge]

SPOCK [OC]: Spock to Captain.
KIRK: Kirk here.

[Engineering]

SPOCK: The force field is gone, Captain. M-5 is neutralised.
SCOTT: System's coming back. I can give you power for the shields, sir.

[Bridge]

KIRK: I need communications.

[Engineering]

SCOTT: That'll take longer.
KIRK [OC]: Then cut power.
SCOTT: Sir!

[Bridge]

KIRK: Cut power. Keep those shields down.

[Lexington Bridge]

WESLEY: The Enterprise looks dead. I'm going to take a chance he's not just laying a trap. Wesley to attack force.

[Bridge]

UHURA: Captain.
WESLEY [OC]: Break off attack. Do not fire. The Enterprise has dropped her shields. I repeat, hold attack. Do not fire.

[Sickbay]

MCCOY: He'll have to be committed to a total rehabilitation centre. Right now he's under sedation and heavy restraints.
SPOCK: I would say his multitronic unit is in approximately the same condition.
KIRK: That's exactly the situation I was hoping for when I forced the M-5 to realise it had committed murder.
(The group walk out of the medical bay to McCoy's office.)
KIRK: Daystrom felt such an act was against the laws of God and man. The computer that carried his engrams also believed it.
SPOCK: Captain, why did you feel the attacking ships would not fire when they saw the Enterprise apparently vulnerable? Logically, that is the sort of trap M-5 should have set.
KIRK: I wasn't sure. Any other commander would have simply followed orders and destroyed us, but I knew Bob Wesley.
(They walk out into the)

[Corridor]

KIRK: I gambled on his humanity.
(and into the)

[Turbolift]

KIRK: Bridge. His logical selection was compassion.
MCCOY: Compassion. That's the one thing no machine ever had. Maybe it's the one thing that keeps men ahead of them. Care to debate that, Spock?
SPOCK: No, Doctor. I simply maintain that computers are more efficient than human beings, not better.
MCCOY: But tell me, which do you prefer to have around?
SPOCK: I presume your question is meant to offer me a choice between machines and human beings, and I believe I have already answered that question.
MCCOY: I was just trying to make conversation, Spock.
SPOCK: It would be most interesting to impress your memory engrams on a computer, Doctor. The resulting torrential flood of illogic would be most entertaining.

[Bridge]

KIRK: Mister Sulu, take us back to the space station. Ahead, warp factor two.