In post-apocalyptic New York, three tribes of survivors (the Norms, the Mutates and the Upriver People) vie for the right to exist. When the treacherous Upriver People attack the Norms, kill their chief and take their people captive, two Norm refugee men must find a way to ally with the Mutates, who have previously kidnapped Norm women in an effort to reproduce healthy children, to rout the Uprivers, who also seek to kill off the Mutates.