The Ultimate Computer

Plot

The Enterprise is called to a space station with no reason given. Commodore Wesley reveals the ship will test the M-5 Multitronic System, a new tactical and control computer invented by Dr. Richard Daystrom. This computer is meant to run every ship function without any human input. Spock finds the M-5 impressive, but Kirk and Dr. McCoy are skeptical.

The M-5 handles its first tasks faster and better than a human crew. Yet it shows odd behavior, like cutting power and life support to empty sections of the ship and pulling extra power for unclear reasons. Daystrom insists this is normal, claiming the computer is just saving energy. Spock and Kirk debate whether Spock would rather serve under a computer or under Kirk.

During a practice drill, the M-5 defends the Enterprise against simulated attacks from the Excalibur and Lexington. The Enterprise wins, and Wesley jokingly calls Kirk a "Captain Dunsel," a Starfleet Academy term for a useless part. This bothers Kirk. Later, the M-5 spots the Woden, an unmanned freighter, and suddenly changes course to attack it with live torpedoes, destroying it.

Kirk tries to shut down the M-5 but finds it protected by a strong force field. Scott orders Ensign Harper to cut its power, but the M-5 links directly to the warp engines, vaporizing Harper. Spock and Scott attempt a manual override but discover the M-5 has taken over all controls. Spock questions Daystrom about the design, and Daystrom admits he copied human engrams into the M-5's circuits, creating a human-like mind running at computer speed.

Meanwhile, four other starships—Lexington, Potemkin, Excalibur, and Hood—arrive for a new drill. With communications disabled by the M-5, Kirk cannot warn them.

The M-5 detects the ships and attacks with full weapons. The crew watches helplessly as the Enterprise fires on the Lexington, killing 53 people, then turns on the Excalibur, killing everyone aboard and leaving it drifting. Commodore Wesley believes Kirk is responsible and asks Starfleet Command for permission to destroy the Enterprise.

Production and reception

In 2011, this episode was noted by Forbes as one of the top ten episodes of the franchise that explores the implications of advanced technology, in particular the danger of A.I. In 2016, SyFy ranked guest star William Marshall's performance as Dr. Daystrom as the 14th best guest star on the original series. The original draft was given to Ray Bradbury by mathematician and Star Trek fan Laurence Wolfe to give to Gene Roddenberry. Michelle Erica Green of Trek Today maintains that it is one of McCoy's best episodes and praises the episode for taking place entirely on the Enterprise. She states that the M-5 turns out to be one of Trek's best villains.