Episode 4
Mirror, 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.
September 22, 1967
The crew of the Enterprise are held captive by an alien who turns out to be the Greek god Apollo.
Episode 3
The Changeling
September 29, 1967
The crew of the USS Enterprise deals with an indestructible planet-destroying space probe.
Episode 4
Mirror, Mirror
October 6, 1967
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.
Episode 5
The Apple
October 13, 1967
The crew of the Enterprise visits a mysterious paradisical planet controlled by a computer that is served by the local inhabitants.
Episode 6
The Doomsday Machine
October 20, 1967
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.
Episode 7
Catspaw
October 27, 1967
Two powerful aliens threaten the well-being of the Enterprise and her crew.
Episode 8
I, Mudd
November 3, 1967
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.
Episode 9
Metamorphosis
November 10, 1967
A shuttle crew from the USS Enterprise encounters a man out of history and his mysterious alien companion.
Episode 10
Journey to Babel
November 17, 1967
The Enterprise must transport dignitaries to a peace conference, with an assassin on the loose.
Episode 11
Friday's Child
December 1, 1967
The crew of the Enterprise become entangled in a planet's tribal power struggle.
Episode 12
The Deadly Years
December 8, 1967
Strange radiation exposes the command crew of the Enterprise to the effects of rapid aging.
Episode 13
Obsession
December 15, 1967
Captain James T. Kirk becomes obsessed with destroying a deadly entity he once encountered in his youth.
Episode 14
Wolf in the Fold
December 22, 1967
A series of bizarre murders points to Mr. Scott as the prime suspect.
Episode 15
The Trouble With Tribbles
December 29, 1967
The Enterprise must protect a very important shipment of grain from both Klingons and some adorable creatures called tribbles.
Episode 16
The Gamesters of Triskelion
January 5, 1968
Captain Kirk and his companions are abducted into slavery and trained to fight as gladiators for the gambling entertainment of three disembodied beings.
Episode 17
A Piece of the Action
January 12, 1968
The Enterprise visits a planet with an Earth-like 1920s gangster culture.
Episode 18
The Immunity Syndrome
January 19, 1968
The crew of the Enterprise encounters an energy-draining field which may be able to destroy the galaxy.
Episode 19
A Private Little War
February 2, 1968
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.
Episode 20
Return to Tomorrow
February 9, 1968
Ancient alien minds are given control of Captain Kirk's and First Officer Spock's bodies.
Episode 21
Patterns of Force
February 16, 1968
The crew of the Enterprise tracks down a Federation observer on a planet dominated by a "Naziesque" regime.
Episode 22
By Any Other Name
February 23, 1968
Beings from another galaxy commandeer the Enterprise in an attempt to return home.
Episode 23
The Omega Glory
March 1, 1968
Captain Kirk must find the cure to a deadly disease and put an end to another Starfleet captain's cultural interference.
Episode 24
The Ultimate Computer
March 8, 1968
A skeleton Enterprise crew are assigned to test a revolutionary computer system that is given total control of the ship.
Episode 25
Bread and Circuses
March 15, 1968
The Enterprise crew investigates the disappearance of a ship's crew on a planet that is a modern version of the Roman Empire.
Episode 26
Assignment: Earth
March 29, 1968
While back in time observing Earth in 1968, the Enterprise crew encounters the mysterious Gary Seven who has his own agenda on the planet.
