E1 - Amok Time

Aired: September 15, 1967

First Officer Spock returns to his home world for a brutal Vulcan mating ritual.

E2 - Who Mourns for Adonais?

Aired: September 22, 1967

The crew of the Enterprise are held captive by an alien who turns out to be the Greek god Apollo.

E3 - The Changeling

Aired: September 29, 1967

The crew of the USS Enterprise deals with an indestructible planet-destroying space probe.

E4 - Mirror, Mirror

Aired: October 06, 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.

E5 - The Apple

Aired: October 13, 1967

The crew of the Enterprise visits a mysterious paradisical planet controlled by a computer that is served by the local inhabitants.

E6 - The Doomsday Machine

Aired: 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.

E7 - Catspaw

Aired: October 27, 1967

Two powerful aliens threaten the well-being of the Enterprise and her crew.

E8 - I, Mudd

Aired: November 03, 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.

E9 - Metamorphosis

Aired: November 10, 1967

A shuttle crew from the USS Enterprise encounters a man out of history and his mysterious alien companion.

E10 - Journey to Babel

Aired: November 17, 1967

The Enterprise must transport dignitaries to a peace conference, with an assassin on the loose.

E11 - Friday's Child

Aired: December 01, 1967

The crew of the Enterprise become entangled in a planet's tribal power struggle.

E12 - The Deadly Years

Aired: December 08, 1967

Strange radiation exposes the command crew of the Enterprise to the effects of rapid aging.

E13 - Obsession

Aired: December 15, 1967

Captain James T. Kirk becomes obsessed with destroying a deadly entity he once encountered in his youth.

E14 - Wolf in the Fold

Aired: December 22, 1967

A series of bizarre murders points to Mr. Scott as the prime suspect.

E15 - The Trouble With Tribbles

Aired: December 29, 1967

The Enterprise must protect a very important shipment of grain from both Klingons and some adorable creatures called tribbles.

E16 - The Gamesters of Triskelion

Aired: January 05, 1968

Captain Kirk and his companions are abducted into slavery and trained to fight as gladiators for the gambling entertainment of three disembodied beings.

E17 - A Piece of the Action

Aired: January 12, 1968

The Enterprise visits a planet with an Earth-like 1920s gangster culture.

E18 - The Immunity Syndrome

Aired: January 19, 1968

The crew of the Enterprise encounters an energy-draining field which may be able to destroy the galaxy.

E19 - A Private Little War

Aired: February 02, 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.

E20 - Return to Tomorrow

Aired: February 09, 1968

Ancient alien minds are given control of Captain Kirk's and First Officer Spock's bodies.

E21 - Patterns of Force

Aired: February 16, 1968

The crew of the Enterprise tracks down a Federation observer on a planet dominated by a "Naziesque" regime.

E22 - By Any Other Name

Aired: February 23, 1968

Beings from another galaxy commandeer the Enterprise in an attempt to return home.

E23 - The Omega Glory

Aired: March 01, 1968

Captain Kirk must find the cure to a deadly disease and put an end to another Starfleet captain's cultural interference.

E24 - The Ultimate Computer

Aired: March 08, 1968

A skeleton Enterprise crew are assigned to test a revolutionary computer system that is given total control of the ship.

E25 - Bread and Circuses

Aired: 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.

E26 - Assignment: Earth

Aired: 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.