The crew of the Enterprise pursues a mysterious woman who has abducted Spock's brain.

An apparently insane Capt. Kirk has the Enterprise deliberately enter the Romulan Neutral Zone where the ship is immediately captured by the enemy.

Trapped on a planet whose inhabitants resemble the Northwestern American Indians Kirk loses his memory and is proclaimed a God while the crippled Enterprise races back to the planet before it is destroyed by an asteroid.

The Enterprise reaches a Federation colony where the adults have all killed each other but the children play without care.

Telepath Miranda escorts an alien ambassador so hideously ugly that the sight of him can drive a Human insane.

As punishment for trespassing on their planet, the inhabitants condemn Capt. Kirk and his landing party as the losing side of a surreal recreation of the Gunfight at the OK corral.

An entity traps the Enterprise crew and the crew of a disabled Klingon battle cruiser in an unending war aboard the Enterprise.

The Enterprise discovers an apparent asteroid that is on a collision course with a planet is actually an ancient populated generation ship.

Kirk and the derelict starship Defiant vanish into a spatial interphase between universes. To rescue him, Spock must maintain position despite a growing, violent hysteria aboard the Enterprise like that which destroyed the Defiant's crew, as well as a force field being laid around the Enterprise by Tholian patrol ships.

On an urgent medical emergency Kirk, Spock and McCoy encounter an alien society who had once flourished on earth during the time of Plato. Since reaching their current planet they had developed psychokinetic powers while also losing the ability for their bodies to combat even the simplest infections. When Doctor McCoy refuses their offer to stay, they begin make sport with Kirk, McCoy, Nurse Chapel and Lieutenant Uhura using their psychokinetic powers.

A group of aliens who exist in a state of incredible acceleration invade the Enterprise and abduct Capt. Kirk.

Trapped in an alien laboratory Kirk, Spock and McCoy meet an empath and are involved in a series of experiments.

The Enterprise transports Elaan, a member of the ruling dynasty of the warrior Elasians, to the planet of their enemy, the Troyians, so that her arranged marriage will halt their interplanetary war. Kirk must teach the arrogant, vicious princess the ways of polite society but falls victim to the legendary weapon of Elasian women: their tears act as a love potion. Spock tracks what may be another ship shadowing the Enterprise and Kirk, distracted by Elaan, must fight against other parties interested in preventing the Federation's peace efforts.

Kirk and Spock are taken prisoners by a former starship captain named Garth, who now resides at, and has taken over, a high security asylum for the criminally insane.

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

Kirk beams down to the planet Gideon and appears to find himself trapped on the deserted Enterprise. Spock on the real Enterprise must use his diplomatic skills to deal with the uncooperative inhabitants of Gideon to find the Captian.

After the Enterprise landing party beams down to investigate a geologically interesting planet, their ship is hurled across the galaxy. Kirk and company find a deserted outpost guarded by the deadly image of a beautiful woman.

The Enterprise is on course to install new equipment on Memory Alpha, the central library storage facility for the Federation. Chief Engineer Scott has been working closely on the project with Lieutenant Mira Romaine with whom he has been forming a romantic attachment. The Enterprise encounters a space storm that kills the staff at Memory Alpha and possesses Lieutenant Mira Romaine.

When Kirk, Spock and McCoy beam down to a supposed uninhabited planet to gather the mineral ryetalyn to fight a plague of Rigelian fever on-board the Enterprise, they find a fellow earth-man called Flint and his extremely intelligent female ward Rayna who Kirk begins to fall in love with. Flint then proceeds to trap them on his planet and takeover the Enterprise.

The Enterprise picks up a group of renegades who have rejected modern technological life to search for the mythical planet Eden.

Kirk and Spock are caught up in a revolution on a planet where intellectuals and artists live on a utopian city in the sky while the rest of the population toils in mines on the barren surface below.

Kirk, Spock, Abraham Lincoln, and Surak are pitted in battle against four notorious villains from history for the purpose of helping a molten rock creature's understanding of a concept he does not understand, 'good verses evil'.

When Kirk, Spock and McCoy investigate the disappearance of a doomed planet's population, they find themselves trapped in different periods of that world's past.

Captain Kirk's insane ex-lover Dr. Janice Lester forcibly switches bodies with him in order to take command of the Enterprise.