Undergoing pon farr, Spock must return to Vulcan to marry or else he will die. Kirk is forced to ignore Starfleet orders and divert the Enterprise to Vulcan to help his science officer only to find that Vulcan tradition pits him against Spock against in a battle to the death.
Who Mourns for Adonais?
Approaching the planet Pollux IV, the Enterprise is captured by a gigantic energy field shaped like a hand, the act of an alien claiming to be the Greek god Apollo. When Kirk refuses to worship the alien, the crew must overcome the powerful “god” in order to escape.
While investigating the destruction of all life in the Malurian System the Enterprise discovers an ancient Earth probe that believes its mission is to destroy imperfect life forms. Kirk must find a way to stop the probe before it annihilates other civilizations.
When a lightning storm causes a transporter malfunction, Kirk, Scotty, McCoy, and Uhura find themselves back on a strange parallel Enterprise where military conquest is a way of life and their mission is to destroy the very people with whom they were negotiating.
While scouting Gamma Trianguli VI, the Enterprise discovers a primitive society living in a Garden of Eden-like paradise. But when a crewman is killed, the landing party find themselves in danger and Kirk discovers that these people are controlled by a less-than-divine power.
The Doomsday Machine
Responding to a distress signal from the L-370 system, the Enterprise discovers her sister ship, the Constellation, wrecked and adrift. When an investigation uncovers the existence of a planet-destroying superweapon, Kirk must find a way to destroy this doomsday machine.
Crewman Jackson is dead! While exploring the planet Pyris VII, the landing party falls victim to a mysterious attack. When Kirk beams down to search for his missing crewmen he discovers a black cat, a spooky castle, and two bizarre individuals on this lifeless, fogbound world.
A crewman commandeers the Enterprise and sets a course for a Class K planet where Kirk encounters Harry Mudd, who has been sent to prison after his their encounter. Now ruler of this planet of androids, Mudd seeks to exact revenge of Captain Kirk by imprisoning him.
On a mission to evacuate a federation commissioner for medical treatment, Kirk, Spock, and McCoy are swallowed up by a mysterious cloud and find themselves on an isolated asteroid where they find the long-lost inventor of warp drive, Zefram Cochrane.
Journey to Babel
While transporting delegates from many Federation worlds to the planet Babel for a conference, the death of the Tellarite Ambassador reignites old rivalries between the Vulcans, Andorians, Tellarites, and Terrans, resulting in the threat of all out war.
The Klingons are after a rare mineral resource on Capella IV. Fighting off a Klingon attack, Kirk must convince the Capellans that they should choose to allow the Federation, rather than the Klingons, access to the planet’s valuable resources.
The Deadly Years
On a resupply mission to the Federation colony on Gamma Hydra IV, the landing party makes a bizarre discovery: the group of young colonists are dying of old age. Upon returning to the ship, members of the landing party begin to exhibit signs of accelerated aging themselves.
While conducting a survey mission on Argus X, members of the security team are found dead, drained of all red corpuscles. When the investigation brings the crew face-to-face with a vampiric cloud, Kirk becomes obsessed with revenge over a similar past encounter.
Wolf in the Fold
Routine shore leave becomes a life and death struggle for Scotty when he is accused of the murder of women on Argelius II. As Kirk, Spock, and McCoy work to exonerate their engineer, they uncover a connection between these murders and others on ancient Earth.
The Trouble with Tribbles
Summoned on emergency channel by Deep Space Station K-7, the Enterprise races to intervene in what is believed to be a Klingon attack. However Kirk soon finds himself caught up in a dispute over grain while small furry creatures threaten to overrun the station.
The Gamesters of Triskelion
Upon entering orbit around the planet Gamma II, Kirk, Uhura, and Chekov are abducted by aliens who take them to a distant world where they are forced to participate in deadly fights for the enjoyment of a superior alien race that gambles on the outcome.
A Piece of the Action
Sent to investigate the disappearance of the Earth ship Horizon, the Enterprise find a society on Sigma Iotia II based on the gangster culture of 1920s Chicago. Trapped on the planet, Kirk and Spock must play the part of mob bosses to cut a deal that allows them to escape.
The Immunity Syndrome
As entire star systems in Sector 39J vanish, Spock senses the death of the all-Vulcan crew of the USS Intreprid. Starfleet orders the Enterprise to investigate a “zone of darkness” where the crew discovers a giant amoeba on a feeding frenzy that threatens the galaxy.
A Private Little War
During a scientific mission to a pre-warp civilization, Spock, Kirk, and McCoy discover that the Klingons have been interfering with this primitive culture by supplying them with advanced weaponry and playing one side against the other, sparking an arms race.
Return to Tomorrow
In orbit around a dead Class M planet, a being named Sargon calls out telepathically to Kirk and Spock to ask for help. When they beam down, Sargon and two companions take over the bodies of Kirk, Spock, and Dr. Mulhall in an attempt to take over the Enterprise.
Patterns of Force
Sent to the planet Ekos to pick up a Federation cultural observer, the Enterprise is attacked by a thermonuclear warhead while attempting to enter orbit and finds a society transformed into a near mirror of Nazi Germany bent on destroying the neighboring world of Zeon.
By Any Other Name
Responding to a distress call, the Enterprise encounters scouts from the Andromeda Galaxy searching for a new home for the Kelvan Empire. When the aliens begin killing Kirk’s crew, the Captain and Spock must find a way to overcome the powerful aliens.
The Omega Glory
After finding the USS Exeter adrift in orbit around Omega IV, its crew missing, Kirk leads the away team down to the planet to investigate only to find an iron-age society fighting against primitive enemies called the “Yangs” who worship the American flag.
The Ultimate Computer
To test a new tactical computer developed by Richard Daystrom, the Enterprise engages in war games to determine if the new M-5 can run a starship without personnel. But the games turn deadly when M-5 locks out the crew and destroys the USS Excalibur.
Bread and Circuses
When the wreckage of the SS Beagle is found near planet 892-IV, Kirk leads an away team to investigate. Soon they are arrested and are forced to participate in gladiator fights in a society that blends 20th-century Earth technology with Ancient Roman culture.
On a historical research mission to the year 1968, the crew seeks to learn how Earth managed to survive the nuclear arms race. But things go awry when they encounter a secret agent who claims to be sent by an advanced civilization to help Earth avoid World War III.