Captain Kirk has a second run-in with the conman, Harry Mudd. Mudd is now the supreme ruler of a planet of androids who cater to his every whim.

Captain Kirk and his companions are abducted into slavery and trained to fight as gladiators for the gambling entertainment of three disembodied beings.

The Enterprise visits a planet with an Earth-like 1920s gangster culture.

The crew of the Enterprise discovers Klingon interference in the development of a formerly peaceful planet and is forced to help maintain a balance of power.

Ancient alien minds are given control of Captain Kirk's and First Officer Spock's bodies.

A skeleton Enterprise crew are assigned to test a revolutionary computer system that is given total control of the ship.

The Enterprise crew investigates the disappearance of a ship's crew on a planet that is a modern version of the Roman Empire.

While back in time observing Earth in 1968, the Enterprise crew encounters the mysterious Gary Seven who has his own agenda on the planet.