Lucid Technologies has a problem. Its secret research into dimensional travel has been sabotaged by fanatics, and the multimillion-dollar facility is now only a bombed-out crater. But where are the terrorists? They've been blown into alternate dimensions, victims of the very technology they sought to destroy. The heroes must track the interdimensional castaways through superspace, traveling through parallel worlds that run the gamut from primitive savagery to nuclear desolation. If the heroes fail in their quest to end the terrorists' rampage through alternate dimensions, there's no predicting the consequences! Suitable for three to six heroes of any levels. Parallel universes are not just science fiction - physics and mathematics predict worlds that resemble and perhaps even duplicate out own. Infinite parallel universes coexist with ours, each with qualities both familiar and foreign, and alternative versions of history play out in endless variety "alongside" out own world. This sourcebook provides a framework for interdimensional adventuring in these parallel worlds, including information on how to create and travel through one parallel universe after another. The book also contains examples of unique sites, phenomena, and superspace travelers for use in any ALTERNITY campaign.