In a lake at a rock quarry, a young woman, Mandy Pullman, and her boyfriend, Roy, are swimming. The two spend the night at the lake camping, but are attacked by an unseen figure; Roy is killed, and Mandy violently raped. Mandy is taken to the hospital with a uterine rupture and serious trauma. As the attack occurs, teenager Tim Galen experiences a recurring nightmare he has in which a woman is tortured by a monstrous figure; his grandmother, Agatha Galen, tries to dissuade him of his suspicions about the premonition dream. At the hospital, Mandy is treated by Dr. Sam Cordell, a surgeon and physician in the small community of Galen.