The movie centers on John Crenshaw, who joins his girlfriend and her students for a weekend trip focused on nature photography in a remote forest. What is meant to be an enjoyable and informative outing quickly descends into terror when the group is attacked by a terrifying force—a swarm of grotesquely deformed, mutated humans with an unquenchable thirst for blood. As the situation deteriorates, Crenshaw emerges as their sole chance for survival.