A cataclysmic event has blackened the sky, plunging the earth into an endless winter. Toxic clouds turned rain to acid, crops can't grow, and the human race is all but extinct. Deep in the dying forest Son and his Father eke out an existence scavenging the wreckage of the former world. Though their lives are bleak, they have each other. But when Son's girlfriend is struck down by an infection, everything falls apart. A group of violent cannibals descend on their safe haven, take the antibiotics keeping his girlfriend alive, and a treacherous journey into the unknown begins.