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.

In his basement in San Francisco, boy-genius Quinn Mallory unlocks the doorway to an infinite number of Earths. During a test run, Quinn invites co-worker Wade Welles and his teacher Professor Maximillian Arturo to see his new invention. But an increase in power and an early departure leave all three, plus a washed-up soul singer named Rembrandt "Crying Man" Brown, lost in a parallel world. Now they must "slide" from world to world, not only adapting to their changing surroundings, but also trying to get back to their world. Will they ever make it home?

Can you tell the difference between fact and fiction? Several stories of strange, mysterious and incredible occurrences are chronicled during each episode. It is up to the viewer to decide which stories actually happened and which were completely fabricated by the show’s writers. The answer is revealed by Jonathan Frakes at the conclusion of each episode.