When a mysterious alien race destroy an Earth colony, the Enterprise pursues, but Kirk and the alien captain are forced to fight each other by powerful aliens.

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 investigates a series of grisly murders on a mining planet that are the work of a seemingly hostile alien creature.

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

First Officer Spock returns to his home world for a brutal Vulcan mating ritual.

The crew of the Enterprise visits a mysterious paradisical planet controlled by a computer that is served by the local inhabitants.

Two powerful aliens threaten the well-being of the Enterprise and her crew.

The Enterprise must transport dignitaries to a peace conference, with an assassin on the loose.

The crew of the Enterprise become entangled in a planet's tribal power struggle.

Strange radiation exposes the command crew of the Enterprise to the effects of rapid aging.

A series of bizarre murders points to Mr. Scott as the prime suspect.

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

The crew of the Enterprise encounters an energy-draining field which may be able to destroy the galaxy.