Kirk and a landing party are stranded on a planet due to a disease that causes any adult to die a painful death, and must deal with the local children who have survived.

Kirk investigates an experimental facility for holding prisoners and finds a sinister scheme.

Kirk pits the Enterprise against an invisible spaceship testing the Federation's defenses.

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

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

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.