Exploring a dangerous and mysterious region of space known as the Delta Triangle, the Enterprise is attacked by Klingon ships. The Enterprise follows one of the Klingon ships into an anomaly and finds itself in another dimension. Both Kirk and the Klingon captain, Kor, are put on trial by the inhabitants of this dimension, called Elysia, made up of species from all over the galaxy. Their leader, a Vulcan named Xerius, explains that nobody has ever been able to escape from this area, so the descendants of the crews have learned to co-exist in a peaceful state. Can Kirk and Kor combine their forces and find a way back to their own universe?
One of the better TAS episodes, this has obvious parallels to Voyager's "The Void" - maybe the writers of that episode were inspired by this one? Seeing how all the different species trapped in Elysia have come to work together is nice, although personally I prefer the Voyager approach where we actually got to see Janeway building her alliance from the start. It's also interesting that Kirk and Kor had to work together, not the first time that Kirk would have to work alongside a Klingon to overcome a common threat.