The Galileo, under Spock's command, crash-lands on a hostile planet. As the Enterprise races against time to find the shuttlecraft, Spock's strictly logical leadership clashes with the fear and resentment of his crew.
For bringing hostility into their solar system, a superior alien race brings Captain Kirk into mortal combat against the reptilian captain of an alien ship he was pursuing.
Seeking the answer to a century-old mystery, Kirk and crew encounter a vacantly peaceful society under a 6000-year autocratic rule that kills all those it can't absorb.
While on patrol in deep space, Captain Kirk and his crew find and revive a genetically-engineered world conqueror and his compatriots from Earth's Twentieth Century.
Kirk and Spock must save their ship's crew when they are all declared killed in action in a bizarre computer simulated war where the actual deaths must nevertheless occur.
Existence itself comes under threat from a man's power-struggle with his alternate self, with the Enterprise's strained dilithium crystals presenting his key to a final solution.
When a temporarily insane Dr. McCoy accidentally changes history and destroys his time, Kirk and Spock follow him to prevent the disaster, but the price to do so is high.
A powerful artificially intelligent Earth probe, with a murderously twisted imperative, comes aboard the Enterprise and mistakes Capt. Kirk for its creator.
A transporter accident places Captain Kirk's landing party in an alternate universe, where the Enterprise is in the service of a barbarically brutal empire.
The USS Enterprise encounters the wrecked USS Constellation and its distraught commodore who's determined to stop the giant planet-destroying robot ship that killed his crew.
Very alien visitors to our galaxy attempt to connect with human consciousness but miss, winding up tapping into the regions of human nightmares instead.
While returning to the Enterprise aboard the shuttlecraft, Kirk, Spock, McCoy and a seriously ill Federation diplomat find themselves kidnapped by an energized cloud.
The Federation clashes with the Klingon Empire over mining rights to Capella IV. A sudden coup between its warrior-minded inhabitants forces Kirk's party to flee with the now dead leader's pregnant wife.
To protect a space station with a vital grain shipment, Kirk must deal with Federation bureaucrats, a Klingon battle cruiser and a peddler who sells furry, purring, hungry little creatures as pets.