Kevin, his older sister, Brittney, and her fiancé, Tony, arrive at their parents' lakeside cabin expecting a leisurely weekend getaway. But their holiday turns into a trip from hell as they enter the scene of a mass shooting where their parents and neighbors all lie dead. Terror strikes when they discover the shotgun-wielding murderer, fresh off a night spent battling demons... or so he claims. They pin him down and lock him in the cellar, but as darkness falls, Kevin begins to entertain the man's ravings about possessed campers and demons in the woods. As unexpected and traumatic events continue to unfold, the family must find a way to survive the night without turning on each other or becoming possessed.