After some mishaps, a group of friends reach a cottage in the woods of Michigan for a quiet weekend. After some dark premonitory signs, the boys find an old book and a tape recorder among the moldering wreckage of the cellar. The book is the Necronomicon, the book of the dead that promises to summon the souls of the damned. The tape contains the voice of an archaeologist, an expert in Sumerian Kabbalah, reciting the book's magical formula. When the tape recorder is turned on and the magical formula is recited in full, the forces of evil are unleashed, and one by one the boys are possessed by the devil and begin to persecute the others, attempting to kill them...