In 2007, the U.S. government successfully sends a probe to an alien world in a parallel universe. The probe starts transmitting video images of the world back to Earth. Then, just minutes into the mission, an alien life form discovers the probe and damages it, causing an unforeseen backlash of energy to create a black hole threatening Earth.
After being briefed on the situation by his old friend Major Vernon, former U.S. Navy SEAL Cutter Slade is given the job of escorting three scientists (William Kauffmann, Anthony Xue and Marion Wolfe) on a mission to this alien world to recover the probe and close the black hole. Arriving in this alien world, Cutter is separated from the other scientists and is hailed by the natives as their messiah, the Ulukai.
Adelpha is a world that is parallel to our own, and it is here that the action of Outcast takes place. The main population are the Talan, basically the parallel version of human beings. Their technology seems very primitive compared to our own; one could say theirs is roughly equivalent to what would have been found in ancient China or medieval Europe. However, their energy-based weapons and intercontinental portals suggest that at one point they were much more advanced.
Adelpha is broken up into several regions, which are hinted to be separated by large water masses. Transport between regions is ensured by gates known as Daokas, which allows its users to instantaneously teleport from one region to another.