In the episode, Spock abducts his former commanding officer, Fleet Captain Christopher Pike, locks the starship Enterprise on a course to the forbidden planet Talos IV and turns himself in for court-martial where he presents an elaborate story explaining his actions.

"The Menagerie" was created as a means to reuse footage from "The Cage" — the unaired 1965 pilot episode of Star Trek — within a frame story as the early history of the Enterprise.

Mendez informs them that Pike could not have sent any message, as a recent accident has left him with locked-in syndrome, unable to move or communicate other than answering yes/no questions with the aid of a device operated by his brainwaves.

After Kirk and Mendez leave to discuss the situation, Spock reveals, over Pike's repeated "no" signals, that he intends to carry out a plan that he has made.

Mendez provides Kirk with classified information on the planet Talos IV, which was visited by the Enterprise previously under Pike's command in 2254, and is now under a strict quarantine.

Spock, meanwhile, commandeers the Enterprise by means of falsified recordings of Kirk's voice, places Pike under McCoy's care, and orders the ship to depart under the computer's control.

[2] After several hours, upon learning from the computer that the shuttlecraft does not have enough fuel to return to the starbase, Spock has them brought aboard and then gives himself up, confessing to mutiny.

Pike beams down to the planet along with Spock and a landing party, where they encounter a group of survivors, including a young woman named Vina, who was born shortly after the crash of Columbia.

A landing party attempts to beam into the complex, but only the female members arrive, in order, as the Talosian "Keeper" explains, to give Pike more choices for a mate.

The court-martial was a ploy to buy time to bring Pike back to Talos IV, where, if willing, he would be able to enjoy the illusion of a normal life.

A message from Commodore Mendez then advises that Starfleet has waived the prohibition against contact with the planet for this one occasion, and that Kirk is free to proceed as he thinks best.

In order to fulfill their series commitment with NBC, Roddenberry wrote a two-part episode that needed only one week of production, and would reuse a large amount of footage from the then-unaired original pilot of Star Trek, "The Cage".

Also in the new scenes, Malachi Throne (who provided the voice of the Keeper in the original "Cage") portrayed Commodore Jose Mendez, while Julie Parrish played personal assistant Miss Piper.

[4] This modified voice would replace Malachi Throne's original voice work in the remastered and new "Original" versions of "The Cage" released later, and allowed the Keeper to then address Captain Kirk by name at the conclusion of part two when he advised Kirk he was hearing the Keeper's thought transmissions and that the invalid Fleet Captain Pike was welcome to live with them unfettered by his physical body.

The Keeper, wishing Kirk a pleasant future, further addresses the captain by name as the illusory fully able-bodied Pike is seen walking with Vina.

Club gave the episode a 'B−' rating, noting that "the whole thing plays out over two hours, and with a framing story from the regular cast that, while dramatic, doesn't quite gel."

[14] On November 13 and 15, 2007, the digitally remastered version of "The Menagerie", in high definition and with Cinema Surround Sound, was released in theatres as a special two-night-only showing.

[citation needed] Some repertory movie theaters in North America showed the classic two-part episode as a feature film in the 1970s.

One such theater, the Seville in Montreal, showed 16mm prints of "The Menagerie" episodes on a big screen as part of a program that concluded with the presentation of the Star Trek blooper reels from seasons one and two.