Dr. Richard Daystrom (William Marshallnote ), creator of computer systems that ships all over Starfleet use, comes aboard to supervise a test of his new M-5 multitronic (?) computer. This computer would obsolete human crew, and cause marked improvements in efficiency among vessels in which it's installed.After a series of tests including a great scare in which M-5 (in control of the Enterprise and activated by a simple flip-switch toggle on the Captain's chair) destroys an unmanned freighter, Kirk is severely concerned that the M-5 is becoming self-aware and possessed of a (severely misdirected) survivor instinct, a point which is driven home when it makes a Red Shirt who tries to unplug it live up to his title.It's then revealed that Daystrom actually imprinted his own memory engrams on the M-5, giving it his human instincts and strategies; but, it turns out, none of his self-control or good sense. Soon the afore-planned wargames start, and M-5, tied into the Enterprise, fatally cripples a manned starship.The head of the games and Kirk's superior, Commodore Wesley, is unable to contact Kirk because M-5 is jamming communications, and assumes Kirk is on a rogue bent. He prepares to fire on the Enterprise even as Daystrom and Kirk are talking to M-5, trying to find out why it did what it did; then McCoy notices that while Kirk is accusing Daystrom of not being thorough enough in transferring his experiences to the M-5, Daystrom is becoming, first arrogant, then quite insane, that his own creation, powered by his own thoughts, could kill people when he himself was a sworn pacifist.Just as the threads of poor Daystrom's psyche begin to unravel, he's treated to a Vulcan neck pinch, then Kirk explains to M-5 that what it's done is murder, and the penalty for murder, as M-5 agrees, is death. M-5 shuts itself down, leaving itself, and the Enterprise, open for attack.Commodore Wesley is just about to give orders to destroy the Enterprise when he notices her shields are down... Hesitating long enough to wonder what's wrong with the Enterprise was what caused our beloved crew to survive. The M-5 is sent back to the drawing board, Daystrom's sent to an asylum and the Enterprise goes on its way, just as inefficient (and just as entertaining) as ever.
- A.I. Is a Crapshoot: And the dice were loaded, given who its "father" was...
- And That's Terrible: Daystrom has to tell the M5 that murder is wrong. Justified, as M5 is a machine, and therefore without compassion, conscience or anything beyond self preservation.
- Brain Uploading: How Daystrom created M5's AI. Spock sarcastically suggests Bones do the same thing, predicting the resulting AI would be completely dysfunctional.
- Cargo Ship: In-Universe between Spock and the M-5.Bones: Did you see the love light in Spock's eyes? The right computer finally came along.
- Catch Phrase: Bones warns Spock against his usual "Fascinating" Catch Phrase. Spock uses "Interesting" instead.
- Curb-Stomp Battle: The M-5 destroys the Excalibur and seriously damages the Lexington, Hood and Potemkin within the first few minutes of the war game exercise. Justified, as none of the other ships expected M-5 to use weapons at full strength.
- Cut the Juice:
- How the Enterprise crew tries to take out M5. Scratch one Red Shirt.
- Later, how Kirk hopes to prevent the Federation battle fleet from destroying the Enterprise since communications are still out.
- Famous, Famous, Fictional: Daystrom is a recipient of "the Nobel and Zee-Magnees prizes", and Kirk compares him to "Einstein, Kazanga, or Sitar of Vulcan". In each case, the first is real and the rest of the list is fictional.
- Forgets to Eat: At first, it looks like Bones is reminding Kirk to eat when he brings in a covered dish. Turns out, he just figured Kirk needed a freaking drink after all that happened.
- Friendship Moment: The other two members of the Power Trio each try to support their captain and friend as he faces the possibility of losing his ship.
Kirk: To Captain Dunsel.McCoy: To James Kirk, Captain of the Enterprise.
Spock: Practical, Captain? Perhaps. But not desirable. Computers make excellent and efficient servants; but I have no wish to serve under them. Captain, a starship also runs on loyalty to one man, and nothing can replace it, or him.
- Future Slang: A "dunsel" is a thing that serves no purpose.
- Glory Days: Daystrom's Freudian Excuse for being so obsessed with the success of the M-5 is that he doesn't want anyone to think he's a Teen Genius who fizzled out.
- Gut Feeling: Kirk has an uncomfortable sensation that something is wrong about M-5, but he wonders if it's just because he's jealous. It isn't.
- Instant A.I., Just Add Water: M-5 starts draining power from the Enterprise to be more powerful.
- Job-Stealing Robot: M-5. Kirk and Bones discuss the history of technology making certain jobs obsolete.
- Logic Bomb: This should just be called The Kirk Maneuver considering how many times Kirk has used this to take out out-of-control computers. In this case, he argues that the M-5 was designed and programmed so that humans wouldn't have to risk themselves in space, and that by murdering the crew of the Excalibur M-5 has violated its own core programming.
- Ludd Was Right: Kirk does not like the idea of his job being taken over by a computer. Especially when M-5 tags him and McCoy as "non-essential personnel" for a landing party.
- Mama Didn't Raise No Criminal: Daystrom stubbornly refuses to admit his computer was at fault - he created it, and he's a pacifist, so his machine should not be able to engage in unprovoked aggression.
- Mildly Military: Kirk is in command of the Enterprise at the end of the episode as it flies back from the war game location to the starbase where the rest of the crew was left. If a current naval vessel so much as dented another during an exercise (let alone effectively destroyed it, like Enterprise did to Excalibur), the captain would be relieved even if it wasn't directly their fault (or, as in Kirk's case, it wasn't remotely his fault at all).
- No Conservation of Energy: this episode correctly predicts that future computers would draw more power for complex tasks than for simple ones, although tapping into the warp engines seems excessive! What's overlooked, however, is that all that energy ends up as heat. M5 is drawing vast amounts of power, yet somehow avoids melting into slag.
- Real Award, Fictional Character: Daystrom is cited as a 2243 Nobel Prize winner for the invention of duotronic computers.
- Reasonable Authority Figure: Commodore Wesley tries to discover what's gone wrong with Enterprise, and when presented with an opportunity to destroy Kirk's ship he orders a stand-down because the Enterprise drops her shields and deactivates her weapons.Kirk: I wasn't sure. Any other commander would have simply followed orders and destroyed us, but I knew Bob Wesley. I gambled on his humanity.
- Redshirt: When M-5 vaporizes one, Daystrom says "M-5 needed more power...the Ensign merely got in the way". At that, Kirk growls "And how long before we all 'just get in the way'?"
- Red Shirt Army: The crews of the other Constitution-class ships. We only meet Commodore Wesley, and the Excalibur's captain is the only other one given a name (when he dies).
- Sanity Slippage: As M-5's murderous misdeeds become more and more impossible to downplay, Dr. Daystrom attempts to rationalize them drive him over the edge until he is raving hysterically and has to be neckpinched into submission.
- Third-Person Person: M-5 always refers to itself as "this unit."
- Unseen Prototype: M-1 through M-4.
- Vitriolic Best Buds: Spock and Bones snipe each other at every opportunity.