Deep in the Andes Mountains, a long-dormant volcano stirs to spectacular life. It threatens to uncover a deadly secret - a lost colony of Predators living in a subterranean world, completely isolated from the rest of the planet until now, when volcanic activity threatens to reveal them, as well as the Aliens who have become part of their ecosystem.
Batman and Superman are faced with a terrible dilemma. They cannot allow the Earth - the humanity they are dedicated to protecting - to be faced with the horrible consequences of contact with these races. But they cannot deny that these species, repugnant as they are to us, are not truly evil but have a right to live, although by following their mandate to survive, they pose a threat such as mankind has never faced before.