Captain Christopher Pike
Jeffrey Hunter

Vina
Susan Oliver

Number One
Majel Barrett

Navigator Jose Tyler
Peter Duryea

Dr. Phillip Boyce
John Hoyt

Yeoman Colt
Laurel Goodwin

CPO Garrison
Adam Roarke

Transporter Chief Pitcairn
Clegg Hoyt

Dr. Theodore Haskins
Lon Lormer

The Keeper
Meg Wyllie

The U.S.S. Enterprise, now under the command of Captain Christopher Pike who succeeded Captain Robert April, receives a primitive distress signal which apparently originates from a survey ship which was lost eighteen years previously. Pike is considering resigning his commission after losing three crew members on an incident on Rigel VII and confides to the ship's surgeon, Doctor Boyce, that his only interest is in getting his damaged ship and crew back to the starbase at the Vega colony.

Spock manages to change his mind by pointing out that there could be survivors from the survey ship S.S. Columbia on the planet Talos IV, which is in an unexplored star system. Pike leads a landing party down which discovers a group of elderly men, the leader of which, Dr. Theodore Hask, confirms that they are from the Columbia. Pike is introduced to a beautiful young girl called Vina who, they say, was born shortly before the accident and whose parents were killed in the crash. She leads Pike away from the group in order to show him their 'secret' but suddenly disappears, along with all the other survivors, and Pike is subdued by some type of gas.

He wakes up in a transparent cell that appears to be built into an underground cavern and finds that he is being observed by a trio of aliens. The Talosians are small-bodied creatures with extremely large, bald craniums and the leader of the group, who is called The Keeper, speaks to him telepathically. Pike is subjected to a series of illusory scenarios, each one containing the girl Vina, in an attempt to lure them together and mate. Pike eventually realises what is happening to him and starts to acquire more information about his captors from Vina who, apparently, is real. In time he discovers that the Talosians' telepathic powers cannot read his thoughts through primitive emotions such as anger.

When they find that their plan is not succeeding, the Talosians transport two of the female Enterprise crewmembers, Yeoman Colt and Number One, down to his cell in the hope that one of them will be more acceptable to him. As they sleep, The Keeper opens a panel in the cell to retrieve the phasers of the two females but Pike is only pretending to sleep and manages to grab hold of him. By threatening him with physical violence Pike forces him to take them all back to the surface of the planet. Vina cautions him that the Talosians are able to create illusions on board the Enterprise that would lead to its destruction. Spock also realises this possibility and tries to move the Enterprise out of range but is prevented from doing so by an illusory power failure.

The Keeper puts Pike through several illusions in an attempt to escape but Pike refuses to let go of him and he eventually gives up, at which point two other Talosians appear before them. They convey the thought that they have examined the ship's computer records and that, combined with Pike's determination to resist captivity, has convinced them that humans are altogether unsuitable for their purposes. Vina is shown to Pike in her true form of an ageing, badly disfigured adult woman who was the only survivor of the Columbia crash. She is offered the chance to leave with Pike but she chooses to stay with the Talosians who promise to let her keep her illusion of youth and beauty. Pike and the crew women return to the Enterprise where he finds that his recent experiences have convinced him to remain as Captain of the Enterprise where he really belongs.

The planet Talos IV is put off limits to all traffic by Starfleet under General Order Number Seven to prevent the Talosians from trying to acquire any different species for their purposes. n.b. This episode was the original pilot episode for the series. Made in 1964 it was rejected by NBC for being too 'cerebral' and, for the first time, asked for a second pilot to be produced which became the episode 'Where no man has gone before'. Much of the footage was used in the making of the double episode 'The Menagerie' where many of the other changes between the pilot and the actual series can be directly compared, most noticeably in the personnel casting and parts / positions portrayed.