 A team of scientists have tampered in a realm of space that was to remain untouched. Guarded by a squadron of money-driven ex-Marine mercenaries called the Iron Bears (led by General Rykov), the scientists and mercenaries find themselves in the middle of a galactic war between a species of aliens and a species known as  Predators.  The story is split into three campaigns, each depicting a different point of view from a different character: an expeditor U.S. Marine (not a member of the mercenary forces), an alien, and a predator.