Stardate: 5267.2--while exploring the Delta Triangle, where many starships have disappeared, the Federation starship Enterprise is attacked by several Klingon vessels. During the battle they are caught in an ion storm. The Enterprise and one Klingon battlecruiser are drawn into a spacetime vortex and end up in a timeless dimension in what could only be called a graveyard for space vessels. Captain Kirk and his crew are shocked to find "that the descendants of the crews of these various vessels are still alive" and have formed a government, calling themselves 'The Elysian Council.'
The crew discovers that the timewarp will gradually disintegrate the Enterprise's dilithium crystals. Their only means of escape is to link their ship with the Klingons' and their commander Kor and try to power themselves out of the vortex.
original airdate--November 24,1973
Alien Races: Phylosian, Andorian, Vulcan, Klingons, Kzin, Orion, Romulan, Gorn, Tellarite, Omega Cygnian, Aquan
Starships: U.S.S. Enterprise NCC-1701
Goofs: Sulu falls out of his chair, but at the very next change of camera angle (an overhead shot of the entire bridge) he is seen still sitting in his chair.
Trivia: This is the last animated episode to feature Klingons, is also the final appearance of the smooth-foreheaded Klingons. Six years and two weeks later, STAR TREK: The Motion Picture debuted in theaters and ushered in the era of the crab-headed "new-look" Klingons.