The film follows John Crenshaw as he accompanies his girlfriend and her students on a weekend nature-photography expedition deep into the woods. What should be an educational and fun-filled weekend turns into horror as the group is besieged by an unspeakable evil - a horde of hideously disfigured, mutated humans with an insatiable taste for blood. As things go from bad to worse, Crenshaw becomes their only hope if they are going to get out alive.