Babylon 5 is a five-mile long space station located in neutral space. Built by the Earth Alliance in the 2250s, its goal is to maintain peace among the various alien races by providing a sanctuary where grievances and negotiations can be worked out among duly appointed ambassadors. A council made up of representatives from the five major space-faring civilizations - the Earth Alliance, Minbari Federation, Centauri Republic, Narn Regime, and Vorlon Empire - work with the League of Non-Aligned Worlds to keep interstellar relations under control. Aside from its diplomatic function, Babylon 5 also serves as a military post for Earth and a port of call for travelers, traders, businessmen, criminals, and Rangers.

Pulled to the far side of the galaxy, where the Federation is 75 years away at maximum warp speed, a Starfleet ship must cooperate with Maquis rebels to find a way home.

Theorizing that one could time travel within his own lifetime, Dr. Sam Beckett stepped into the Quantum Leap accelerator and vanished... He woke to find himself trapped in the past, facing mirror images that were not his own and driven by an unknown force to change history for the better. His only guide on this journey is Al, an observer from his own time, who appears in the form of a hologram that only Sam can see and hear. And so Dr. Beckett finds himself leaping from life to life, striving to put right what once went wrong and hoping each time that his next leap will be the leap home.