A rash of strange deaths in the Tahoe National Forest bring Sam, Dean and Bobby to the Sierra Nevada mountains to hunt a monster with a taste for human flesh. Soon walking corpses, bodies with missing organs, and attacks by a mysterious flying creature lead the trio to a cunning and deadly foe which can assume a human form and will do anything to survive. When a blizzard strikes the area, and not knowing who they can trust, they must battle not only the monster, but also the elements to survive.