Christopher Pike and the U.S.S. Enterprise investigate a crash site on Talos IV, where the captain is imprisoned by powerful telepathic aliens and studied.
Captain Kirk and the Enterprise deliver supplies to planet M-113, where McCoy is reunited with an old flame. A salt-sucking shapeshifter begins attacking the crew.
One of the Enterprise's own crew threatens the ship when an alien energy force gives him god-like powers. Kirk must sacrifice his friend for the good of the galaxy -- if he can.
A transporter accident separates Kirk into two people -- a kind and gentle Kirk, and a strong and unscrupulous Kirk. The crew must reunite the two and restore their captain.
The Enterprise welcomes a freighter captain and three beautiful women, who turn the heads of every man on board -- but who are using a powerful drug to maintain their appearances.
Nurse Chapel is reunited with her long-lost fiancée, who has created a colony of android clones and plans to take over the Enterprise -- and the Federation.
The Enterprise finds a world ravaged by disease, where the only survivors are a group of children -- who themselves suffer and die upon reaching adulthood.
Kirk and the Enterprise crew investigate a penal colony, where the facility's reputable director gives the captain a first-hand look at his neural neutralizer device.
Spock kidnaps his former captain and commandeers the Enterprise, prompting a court martial where he presents the story of Christopher Pike's fateful mission to the planet Talos IV.
Kirk and crew battle an invisible enemy -- a Romulan warbird that has crossed the Neutral Zone and attacked Federation outposts. Spock's loyalties are questioned when the first Romulan visual transmission is intercepted.
Spock, McCoy, Scott and four crewmen crash land on a hostile alien planet, and Kirk must choose between looking for them or delivering desperately-needed medical supplies to a plague-stricken world.
The Enterprise crew is captured by an impetuous and eccentric being with tremendous powers, and Kirk must challenge him to a duel if they hope to escape.
The Enterprise investigates a world where a Federation starship disappeared more than a century before, and find a civilization controlled by a group of "law givers" and the enigmatic Landru.
The crew finds a sleeper ship from the 20th century, and revive a genetically-altered military leader who attempts to take over the ship: the cunning and powerful Khan.
The crew attempt to evacuate a human colony, but spores from a local plant alter their minds, leading to an all-out mutiny. Spock explores his emotional side.
Kirk and Spock come face-to-face with the Klingon Empire during a mission to establish a Federation presence on the planet Organia, and find that the local people have no desire to defend themselves from the Klingons.
The Enterprise finds the pilot of a space-time ship struggling with an evil version of himself from an alternate dimension -- and must stop the destruction of the entire universe.
Dr. McCoy inadvertently changes history, wiping the Federation from existence. Kirk and Spock must follow him through a portal to Earth's 20th century to set things right.
