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

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

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

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

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.

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 Enterprise encounters a vast alien ship that threatens the Enterprise with destruction.

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.

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.

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

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

The Enterprise crew try to rescue colonists from deadly radiation, but instead encounter strange alien spores that seem to offer paradise.

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

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.

Spock commands a stranded away team when their shuttlecraft is stranded on a planet with hostile natives.

Nurse Christine Chapel is reunited with her old fiance on Exo III, but the scientist has plans for Captain Kirk and the Federation.

Kirk and the Enterprise must combat parasitic aliens threatening the lives of millions.

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

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 crew take shore leave on a peaceful, pastoral planet... where their dreams and fantasies come to life.

Kirk and his crew are at deadly risk from an alien creature that feeds on the salt in a human body and can take on any form.

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

Kirk is one of the last survivors who can identify a mass killer, who lurks among a Shakespearean troupe aboard the Enterprise.

The Enterprise encounters a seemingly peaceful civilization run by a "benevolent" being named Landru... who intends for them to join his people.