Executive Producer: Gene Roddenberry
Producers: Gene L. Coon + John Meredyth Lucas
Associate Producer: Robert H. Justman
Script Consultant: D. C. Fontana

Writer: John M. Lucas
Dir.: Marc Daniels

Captain Kirk: William Shatner
Science Officer, First Officer, Cmdr. Spock: Leonard Nimoy
Dr. Leonard "Bones" Mc Coy: DeForest Kelly
Lt. Sulu: George Takei
Lieutenant Commander Montgomery Scott: James Doohan
Lieutenant Uhura: Nichelle Nichols
Nurse Christine Chapel: Majel Barrett
Mr. Singh: Blaisdell Makee
Lt. Carlisle: Arnold Lessing
Nomad’s voice: Vic Perrin

Stardate 3451.9

In the Malurian System four billion inhabitants have been killed. The Enterprise investigates and traces a space probe/computer unit. This unit now heads for the Enterprise with the aim to destroy all faulty, imperfect existence – and is just about to identify the Enterprise as imperfect. When captain Kirk identifies himself, the computer–probe, which calls itself "Nomad", suddenly changes it's mind. It comes on board, instead of destroying the Enterprise. 

In a mindmeld with Nomad, Spock finds out it had been a space probe created by Jackson Roykirk, launched in 2020 to seek out alien life in the galaxy. Later the probe was hit by a meteor which caused the damage in it. Another encounter with an alien probe called Tan-Ru which had been sent to gather sterilized soil samples resulted in a merger of the two. Now Nomad is destroying all imperfect life forms and is quite impressed about Spock, but it labels Scotty "imperfect" and kills him. As Nomad sees Kirk's distress, it offers to restore "the unit Scott" and revives him. Scotty wonders what has happened ... Nomad erases Lt. Uhura's memory because she was humming. She cannot be "restored" and needs to learn all she knew from scrap. 

Kirk can prevent more to happen but the dialogues with Nomad slowly make Nomad beginning to think that Kirk, whom he takes for his creator, might be imperfect, too ... Spock and Kirk clearly see the danger developing and think of a plan (Spock cannot take over because it is Kirk who is allowed to get close to Nomad): Kirk confronts Nomad with a mistake it has done = to think Kirk is his creator. He logically approaches the consequence. Nomad sees it has made a mistake. Kirk now urges it (in order to accomplish his mission to destroy all faulty things) to destroy itself. Nomad realizes to be imperfect. The moment Nomad is about to destroy itself, Kirk and Spock beam it far away into space. The crew sees the explosion from the bridge. Kirk reveals to Spock that he knows about Spock's amazement – he had not expected him to be capable of such logic. Spock does not contradict his captain.

Head picture courtesy of Ultimate Pix