1Amok Time
First Officer Spock returns to his home world for a brutal Vulcan mating ritual.
2Who Mourns for Adonais?
The crew of the Enterprise are held captive by an alien who turns out to be the Greek god Apollo.
3The Changeling
The crew of the USS Enterprise deals with an indestructible planet-destroying space probe.
4Mirror, Mirror
A transporter mishap swaps Captain Kirk and his companions with their evil counterparts in a parallel universe. In the so-called Mirror Universe, the Enterprise is a ship of the Terran Empire, an organization as evil as the United Federation of Planets is benevolent.
5The Apple
The crew of the Enterprise visits a mysterious paradisical planet controlled by a computer that is served by the local inhabitants.
6The Doomsday Machine
The starship Enterprise and its heavily-damaged sister ship, the USS Constellation, must work together to stop an alien planet-killing machine headed for the heart of Federation territory.
7Catspaw
Two powerful aliens threaten the well-being of the Enterprise and her crew.
8I, Mudd
Captain Kirk has a second run-in with the conman, Harry Mudd. Mudd is now the supreme ruler of a planet of androids who cater to his every whim.
9Metamorphosis
A shuttle crew from the USS Enterprise encounters a man out of history and his mysterious alien companion.
10Journey to Babel
The Enterprise must transport dignitaries to a peace conference, with an assassin on the loose.
11Friday's Child
The crew of the Enterprise become entangled in a planet's tribal power struggle.
12The Deadly Years
Strange radiation exposes the command crew of the Enterprise to the effects of rapid aging.
13Obsession
Captain James T. Kirk becomes obsessed with destroying a deadly entity he once encountered in his youth.
14Wolf in the Fold
A series of bizarre murders points to Mr. Scott as the prime suspect.
15The Trouble With Tribbles
The Enterprise must protect a very important shipment of grain from both Klingons and some adorable creatures called tribbles.
16The Gamesters of Triskelion
Captain Kirk and his companions are abducted into slavery and trained to fight as gladiators for the gambling entertainment of three disembodied beings.
17A Piece of the Action
The Enterprise visits a planet with an Earth-like 1920s gangster culture.
18The Immunity Syndrome
The crew of the Enterprise encounters an energy-draining field which may be able to destroy the galaxy.
19A Private Little War
The crew of the Enterprise discovers Klingon interference in the development of a formerly peaceful planet and is forced to help maintain a balance of power.
20Return to Tomorrow
Ancient alien minds are given control of Captain Kirk's and First Officer Spock's bodies.
21Patterns of Force
The crew of the Enterprise tracks down a Federation observer on a planet dominated by a "Naziesque" regime.
22By Any Other Name
Beings from another galaxy commandeer the Enterprise in an attempt to return home.
23The Omega Glory
Captain Kirk must find the cure to a deadly disease and put an end to another Starfleet captain's cultural interference.
24The Ultimate Computer
A skeleton Enterprise crew are assigned to test a revolutionary computer system that is given total control of the ship.
25Bread and Circuses
The Enterprise crew investigates the disappearance of a ship's crew on a planet that is a modern version of the Roman Empire.
26Assignment: Earth
While back in time observing Earth in 1968, the Enterprise crew encounters the mysterious Gary Seven who has his own agenda on the planet.