First Aired September 15, 1967
In the throes of his Pon Farr mating period, Spock must return to Vulcan to meet his intended future wife, betrothed from childhood.
First Aired September 22, 1967
A powerful being claiming to be the Greek god Apollo appears and demands that the crew of the Enterprise disembark onto his planet to worship him.
First Aired September 29, 1967
A powerful artificially intelligent Earth probe, with a murderously twisted imperative, comes aboard the Enterprise and mistakes Capt. Kirk for its creator.
First Aired October 06, 1967
A transporter accident places Captain Kirk's landing party in an alternate universe, where the Enterprise is in the service of a barbarically brutal empire.
First Aired October 13, 1967
Primitive inhabitants of Gamma Trianguli VI worship a god who orders them to kill visitors from the Enterprise.
First Aired October 20, 1967
The USS Enterprise encounters the wrecked USS Constellation and its distraught commodore who's determined to stop the giant planet-destroying robot ship that killed his crew.
First Aired October 27, 1967
Very alien visitors to our galaxy attempt to connect with human consciousness but miss, winding up tapping into the regions of human nightmares instead.
First Aired November 03, 1967
Harry Mudd returns with a plot to take over the Enterprise by stranding the crew on a planet populated by androids under his command.
First Aired November 10, 1967
While returning to the Enterprise aboard the shuttlecraft, Kirk, Spock, McCoy and a seriously ill Federation diplomat find themselves kidnapped by an energized cloud.
First Aired November 17, 1967
The Enterprise hosts a number of quarrelling diplomats, including Spock's father, but someone on board has murder in mind.
First Aired December 01, 1967
The Federation clashes with the Klingon Empire over mining rights to Capella IV. A sudden coup between its warrior-minded inhabitants forces Kirk's party to flee with the now dead leader's pregnant wife.
First Aired December 08, 1967
A landing party from the Enterprise is exposed to strange form of radiation which rapidly ages them.
First Aired December 15, 1967
Capt. Kirk obsessively hunts for a mysterious cloud creature he encountered in his youth.
First Aired December 22, 1967
Kirk and the Enterprise computer become detectives after Scotty is accused of murdering women on a pleasure planet.
First Aired December 29, 1967
To protect a space station with a vital grain shipment, Kirk and the crew must deal with Federation bureaucrats, a Klingon battle cruiser and a peddler who sells furry, purring, voracious little creatures as pets.
First Aired January 05, 1968
Kirk, Uhura and Chekov are trapped on a planet where abducted aliens are enslaved and trained to perform as gladiators for the amusement of bored, faceless aliens.
First Aired January 12, 1968
The crew of the Enterprise struggles to cope with a planet of imitative people who have modeled their society on 1920s gangsters.
First Aired January 19, 1968
The Enterprise encounters a gigantic energy draining space organism that threatens the galaxy.
First Aired February 02, 1968
Peaceful, primitive peoples get caught up in the struggle between superpowers, with Kirk unhappily trying to restore the balance of power disrupted by the Klingons.
First Aired February 09, 1968
The Enterprise is guided to a distant, long-dead world where survivors of an extremely ancient race - existing only as disembodied energy - desiring the bodies of Kirk, Spock and astro-biologist Ann Mulhall so that they may live again.
First Aired February 16, 1968
Looking for a missing Federation cultural observer, Kirk and Spock find themselves on a planet whose culture has been completely patterned after Nazi Germany.
First Aired February 23, 1968
Galactic alien scouts capture the Enterprise for a return voyage and a prelude to invasion. Kirk's one advantage - they're not used to their adopted human form.
First Aired March 01, 1968
Responding to a distress signal, Kirk finds Captain Tracey of the U.S.S. Exeter violating the prime directive and interfering with a war between the Yangs and the Kohms to find the secret of their longevity.
First Aired March 08, 1968
Kirk and a sub-skeleton crew are ordered to test out an advanced artificially intelligent control system - the M-5 Multitronic system, which could potentially render them all redundant.
First 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.
First 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.