In a near-future New York devastated by a catastrophic explosion—the result of a deranged scientist's nuclear and chemical weapon—much of the city's population has been transformed into obedient mutant soldiers. The scientist consolidates his power through an organization called Big Valley, arming these creatures with cutting-edge military technology and ordering them to seize control of the ruins and seal off the city from the outside world. Facing an unprecedented crisis, the U.S. government turns to its last resort: two elite mercenaries with superhuman abilities tasked with infiltrating the occupied metropolis and dismantling the threat from within.