While exploring the edge of the galaxy, the Enterprise encounters an energy barrier that gives two crewmen godlike powers.

A strange alien substance causes the crew to act out their deepest inhibitions, while the ship plummets out of orbit.

A transporter malfunction causes Captain Kirk to split into his "good" and "evil" selves, and a landing party will freeze to death if they don't merge the two back together.

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

The Enterprise encounters a vast alien ship that sets out to test them.

Spock kidnaps his former captain, the crippled Christopher Pike, and heads for a quarantined planet, putting his career and Kirk's life on the line.

Spock's court-martial continues as he attempts to justify his abduction of Pike, the theft of the Enterprise, and his heading for a planet declared forbidden by Starfleet.

Kirk pits the Enterprise against an invisible spaceship testing the Federation's defenses.

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 picks up a crew of genetic supermen from the 20th century, whose leader, Khan, plans to create a new empire.

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.

Spock must go to Vulcan in order to perform the Vulcan mating ritual.

Kirk and three of his officers are accidentally transported into a parallel "mirror" universe where violence, greed, and evil are commonplace.

The Enterprise must stop an ancient doomsday weapon that is capable of destroying entire worlds, and has already totalled one Constellation-class cruiser.

Spock meets his estranged father when the Enterprise escorts a group of ambassadors to a conference on the planet Babel.

Kirk must defuse a Klingon scheme to destroy a grain shipment, and cope with a seemingly benign creature known as a tribble, which reproduces at amazing speed.

The Enterprise travels to a planet suffering from cultural contamination from an earlier expedition - the inhabitants mimic the culture of 1930's gangland Chicago.

The Enterprise must destroy an enormous space amoeba before it reproduces and threatens known space.

The Enterprise arrives at the last known position of the U.S.S. Defiant, an area of uncharted space, to search for the missing starship.

Kirk and his crew find themselves at the mercy of powerful individuals who possess mind-over-matter powers, and plan to use the Enterprise crew for their twisted entertainment.