E1 - Spock's Brain

Aired: September 20, 1968

An alien female beams aboard the ship and, after incapacitating the rest of the crew, surgically removes Spock's brain. Kirk and the crew have just hours to locate and replace it before Spock's body dies.

E2 - The Enterprise Incident

Aired: September 27, 1968

The crew of the Enterprise are on a secret mission to steal a Romulan cloaking device.

E3 - The Paradise Syndrome

Aired: October 04, 1968

An alien device on a primitive planet erases Captain Kirk's memory, and he begins a new life with the planet's indigenous people.

E4 - And the Children Shall Lead

Aired: October 11, 1968

On a distant planet, Kirk, Spock and McCoy find a scientific team dead, and their children who, unknown to the crew, have great powers at their disposal.

E5 - Is There in Truth No Beauty?

Aired: October 18, 1968

The Enterprise travels with an alien ambassador whose appearance induces madness.

E6 - Spectre of the Gun

Aired: October 25, 1968

Having been found trespassers into Melkotian space, Captain Kirk and his companions are sent to die in a re-enactment of the gunfight at the O.K. Corral.

E7 - Day of the Dove

Aired: November 01, 1968

An alien force drives the crew of the Enterprise into brutal conflict with the Klingons.

E8 - For the World Is Hollow and I Have Touched the Sky

Aired: November 08, 1968

The crew of the Enterprise rush to stop an asteroid from colliding with a Federation world, but discover the asteroid is actually an inhabited generation ship.

E9 - The Tholian Web

Aired: November 15, 1968

Captain Kirk is caught between dimensions while the crew of the Enterprise works to retrieve him. All the while, the Tholians demand that the Enterprise leave their space.

E10 - Plato's Stepchildren

Aired: November 22, 1968

The crew of the Enterprise encounters an ageless and sadistic race of humanoids with the power of telekinesis and who claim to have organized their society around Ancient Greek ideals.

E11 - Wink of an Eye

Aired: November 29, 1968

Invisible "time-accelerated" aliens take over the Enterprise and attempt to abduct the crew for use as "genetic stock".

E12 - The Empath

Aired: December 06, 1968

While visiting a doomed planet, the landing party is subject to torturous experiments by powerful aliens.

E13 - Elaan of Troyius

Aired: December 20, 1968

The USS Enterprise ferries a spoiled princess whose betrothal to a royal Troyian is hoped will bring peace to a star system at war.

E14 - Whom Gods Destroy

Aired: January 03, 1969

Captain Kirk faces off with a demented shape-shifting starship captain determined to control the universe.

E15 - Let That Be Your Last Battlefield

Aired: January 10, 1969

The Enterprise encounters two duo-chromatic and mutually belligerent aliens who put the ship in the middle of their old conflict.

E16 - The Mark of Gideon

Aired: January 17, 1969

A race of overpopulated aliens abduct Captain Kirk to solve their problem.

E17 - That Which Survives

Aired: January 24, 1969

Kirk, McCoy, and Sulu are stranded on a barren planet where a mysterious woman attempts to kill them one at a time, while the Enterprise must travel halfway across the galaxy to rescue them.

E18 - The Lights of Zetar

Aired: January 31, 1969

Strange incorporeal aliens threaten the Memory Alpha station and the Enterprise.

E19 - Requiem for Methuselah

Aired: February 14, 1969

The crew of the Enterprise encounter an immortal human in this science fiction variation on Shakespeare's The Tempest.

E20 - The Way to Eden

Aired: February 21, 1969

The Enterprise picks up a group of space "hippies" looking for Eden.

E21 - The Cloud Minders

Aired: February 28, 1969

Captain Kirk races against time to acquire plague-fighting minerals from a world in the midst of a civil uprising against a grievous social class disparity.

E22 - The Savage Curtain

Aired: March 07, 1969

Aliens force Captain Kirk and First Officer Spock to join forces with "Abraham Lincoln" and "Surak" to battle villains in a contest of good vs. evil.

E23 - All Our Yesterdays

Aired: March 14, 1969

Kirk, Spock and McCoy are trapped in two parts of another planet's past - a world threatened with destruction when its sun goes supernova.

E24 - Turnabout Intruder

Aired: June 03, 1969

The Enterprise is in danger when Janice Lester, one of Kirk's former lovers, steals his body.