The film centers around five recent college graduates, Jeff, Karen, Paul, Marcy and Bert, who trek to a remote cabin deep in the woods to celebrate with some wanton sex and copious amounts of alcohol. They are also visited by a stoner camper, Justin (aka Grim), who has a large dog named Doctor Mambo. Bert goes hunting, and accidentally shoots a vagrant in the woods. Although not apparently seriously injured, he is extremely ill with some unknown disease, and Bert leaves him to die. The man later turns up at the cabin, even sicker, asking for their help in seeking medical attention, but when he recognizes Bert, the group panics and turn him away without assistance. He attempts to steal their truck and in the scuffle Paul and Marcy accidentally set him on fire and he runs into the woods where he falls into the cabin's water supply. They one by one fall victim to the disease.