In orbit around a dead star, the Enterprise comes across a huge starship inhabited by a parasitic life form that threatens the entire ship.

Spock must return to his own past on Vulcan to prevent his death as a youngster.

The crew of the Enterprise races to find a way to stop a cloud from destroying inhabited planets.

The men of the Enterprise are victimized by a race of beautiful women who stay immortal by draining the lifeforce of men.

Cyrano Jones returns, along with new tribbles that can't multiply.

The Enterprise finds missing trader and philanthropist Carter Winston, but he may not be what he appears to be.

Kirk and the crew are faced with a race of intelligent plants and a mad scientist who wants to impose peace on the galaxy.

The Enterprise goes to the center of the galaxy, where they find a race of powerful aliens who once fled Earth.

Kirk returns to the "shore leave" planet, but it's not as peaceful as it was when they last saw it.

The crew encounters Harry Mudd again, who is selling a fake love potion.

The Enterprise and a Klingon ship must join forces to escape from a pocket universe that has been trapping starships for centuries.

The crew of the Enterprise finds themselves shrinking after being bathed with radiation.

While exploring the planet Argo, Kirk and Spock are turned into water breathers.

Spock, Sulu and Uhura are captured by the Kzinti, who are trying to learn the secret of an ancient weapon.

While searching for a lost ship, Kirk, Spock and McCoy are captured and placed in a zoo by advanced, telepathic aliens.

Kirk leads a party to retrieve a religious relic that was stolen. However, he is faced with sabotage from within the group by someone who doesn't want the relic to be found, which will trigger an intergalactic jihad.