On a planet populated by children whose aging process has been slowed artificially. Kirk’s landing party members contract a virus that kills adults. Despite their violent attacks, Kirk is determined to help the children.

Crash landing on a planet populated by hostile giants, the 7-man crew of the shuttlecraft Galileo find themselves unable to communicate with the enterprise or to escape the planet's atmosphere.

The Enterprise encounters a seemingly peaceful civilization run by a "benevolent" being named Landru... who intends for them to join his people.

The Enterprise arrives at a planet to establish diplomatic relations and finds itself in the middle of a "peaceful" war that threatens to destroy the ship.

Kirk and Spock must travel into the past in order to correct a change that will alter history.

The Enterprise must protect a very important shipment of grain from both Klingons and some adorable creatures called tribbles.

Captain Kirk must find the cure to a deadly disease and put an end to another Starfleet captain's cultural interference.

The Enterprise is in danger when Janice Lester, one of Kirk's former lovers, steals his body.