A transporter malfunction splits Captain Kirk into two halves: one meek and indecisive, the other violent and ill tempered. The remaining crew members stranded on the planet cannot be beamed up to the ship until a problem is fixed.
The Enterprise picks up untrustworthy entrepreneur Harry Mudd accompanied by three beautiful women who immediately put a spell on all the male crew members.
Kirk and psychiatrist Helen Noel are trapped on a maximum security penal colony that experiments with mind control and Spock must use the Vulcan mind-meld to find a way to save them.
While Captain Kirk investigates whether an actor is actually a presumed dead mass murderer, a mysterious assailant is killing the people who could identify the fugitive.
The past months have left the crew exhausted and in desperate need of a break, but does this explain McCoy's encounter with a human-sized white rabbit or Kirk crossing paths with the prankster who plagued his days at Starfleet Academy?
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.
