Lately, Spock's behavior has been increasingly and unprecedentedly erratic. When McCoy finds it to be a growing medical risk, Kirk drags the truth out of him: it is the ' ...

The Enterprise is stopped dead in its tracks by a powerful energy force that appears in the form of a human hand. Soon, a being claiming to be Apollo orders Kirk (William ...

The Enterprise encounters a powerful energy force that has apparently killed all human life in a solar system with over one billion inhabitants. They identify the culprit ...

Beamed up during an ion storm, which causes a transporter malfunction, the landing party of Kirk, McCoy, Scotty and Uhura find themselves in a mirror universe aboard a pa ...

Kirk and a landing party beam down to what seems to be an ideal, Eden-like planet. They soon find however that the planet is ruled by a powerful computer that keeps its l ...

The U.S.S. Constellation and its crew were destroyed by a giant robot ship which consumes planets for fuel, leaving only a guilt-ridden Commodore Decker aboard the crippl ...

When Captain Kirk and his landing party arrive on Pyrus VII, they are met by eerie mists, a dark castle, wailing witches, zombies and a black cat. They soon learn that th ...

When an android takes control of the Enterprise, Kirk and his crew spend four days traveling at warp speed to an uncharted planet. When they beam down they find none othe ...

The Enterprise shuttlecraft, carrying Kirk, Spock, Dr. McCoy and critically ill Federation Ambassador Nancy Hedford, encounters a mysterious energy cloud which pulls them ...

The Enterprise is transporting several diplomatic delegations to a conference on Babel regarding the future of the mineral-rich planet Coridan. Among the passengers are S ...

The Federation is in competition with the Klingons for an alliance with the inhabitants of Capella IV. The Capellans are a warrior tribe and there is dissension among the ...

Rapid aging afflicts all six colonists on Gamma Hydra IV and five members of Kirk's six-man landing party - all but Chekov. With the Neutral Zone so close, suspicion fall ...

Captain Kirk is haunted by a creature from his past when conducting a mining survey on a planet. He first encountered it as a lieutenant aboard the U.S.S. Farragut and bl ...

While on shore leave on the planet Argelius II with Dr. McCoy and Captain Kirk, Chief Engineer Scott finds himself accused of murdering an exotic dancer he met in a night ...

Having received a Priority One distress call from an outlying space station, the Enterprise arrives to find they have been summoned there by a Federation commissioner mer ...

Kirk, Uhura and Chekov find themselves suddenly transported light years across the galaxy to the planet Triskelion. There, they are trained as thralls, slaves who engage ...

The Enterprise investigates a planet visited 100 years ago by the U.S.S. Horizon. Kirk, Spock, and McCoy beam down and find themselves in a culture similar to Earth gangs ...

The Enterprise is sent to investigate the disruption of the Gamma VII-A solar system and the destruction of the U.S.S. Intrepid, staffed solely by Vulcans. When they arri ...

Kirk returns to the planet where he spent time 13 years before. A friend from his previous visit is now leader of his people. While trying to uphold the Federation's prim ...

From a planet bereft of life for half a million years, the Enterprise hears the voice of Sargon, who is able to control the ship and tells them to transport to specific c ...

The Enterprise searches the reportedly primitive and warlike planet, Ekos, for the missing Federation cultural observer, Professor John Gill (David Brian). When Kirk (Wil ...

Kirk, Spock, McCoy and a couple of red shirts beam down to the surface of a planet in answer to a fake distress call. There they are overpowered by a small group of human ...

As the Enterprise approaches planet Omega IV, they find another starship, the U.S.S. Exeter, in orbit. Kirk, Spock and McCoy beam aboard to find the ship abandoned but st ...

Captain Kirk replies to an urgent (yet brief) message from Commodore Enright, which only tells him to report to the nearest space station. Once there, most of the crew is ...

While searching for the crew of a destroyed spaceship, the Enterprise discovers a planet whose oppressive government is a 20th-century version of Earth's Roman Empire. Ki ...

When the Enterprise is assigned to observe Earth's history in 1968, suddenly it intercepts a transporter beam which originates at least a thousand light-years from Earth, ...