A strange alien substance causes the crew to lose their inhibitions.

The Enterprise picks up a intergalactic conman, Harry Mudd, and three incredibly beautiful women who harbor a dark secret.

Kirk investigates an experimental facility for holding prisoners and finds a sinister scheme.

The Enterprise finds itself at the mercy of a seemingly omnipotent being who fancies himself an 18th century Englishman.

In a freak accident the Enterprise is sent back to 20th century Earth, and must find their way back without changing history.

Captain Kirk's career is at stake when he is put on trial for the loss of a crewman during an ion storm.

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.

The Federation and the Klingon Empire teeter on the brink of war as Kirk investigates Organia, a humble planet, inhabited by pacifists, that is unwittingly caught in the middle.

The crew of the Enterprise are held captive by an alien who turns out to be the Greek god Apollo.

A transporter mishap swaps Captain Kirk and his companions with their evil counterparts in a parallel universe. In the so-called Mirror Universe, the Enterprise is a ship of the Terran Empire, an organization as evil as the United Federation of Planets is benevolent.

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

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 ageless and sadistic race of humanoids with the power of telekinesis and who claim to have organized their society around Ancient Greek ideals.