On September 18, 1972, Dr. Hoffman and his wife, both of whom specialized in the study of telekinesis and the occult, are found dead in their Mulholland Drive ranch home on the night of their anniversary party. Their deaths, ruled a double suicide, were witnessed by the couple's thirteen-year-old daughter, Debbie, who was institutionalized due to a subsequent nervous breakdown. A couple who subsequently purchase the home also befall gruesome, unexplained deaths in it, as does the following buyer, Herman Royce. In 1982, the residence is reopened as a boarding house by Jim Royce, nephew of Herman, who has inherits the home. Jim, a playboy who himself is obsessed with the occult and telekinesis, places a newspaper ad encouraging young, single women to move in. Various young aspiring actresses and models—Sandy, Suzie, Cindy, Gloria, Pam, and Terri—respond and move into the home. After they settle in, an English woman, Debbie, arrives, pleading to move in; she agrees to stay into the sole remaining cramped spare room in the house. Meanwhile, Detective Richard Grant is casing the home for unknown reasons. He sends a private investigator to the house, but he is electrocuted in a bathtub before being buried in the backyard by an unseen assailant. Meanwhile, Jim exhibits his own telekinetic powers to Victoria, an aspiring singer. She is fascinated by his abilities. That night, she suffers a vivid nightmare of being dragged into the grave of Dr. Hoffman. Richard eventually arrives at the house to visit Cindy, who is revealed to be his ex-girlfriend. Richard chastises Cindy for new living arrangement and for having fled upon his marriage proposal. Inspired by Jim and jealous of the other women in the house, Victoria begins attempting to hone her own supernatural powers. She soon discovers she too has the ability to harness telekinesis. Cindy mysteriously vanishes on the beach while having a rendezvous with Jim. A note left behind indicates she has reunited with Richard. The next day, Jim and the women prepare for a housewarming party they are holding that night. While cleaning the house, Victoria suffers another terrifying vision in which a looming, monstrous entity chases her through the house. Later, she finds her pet cat, Pumpkin, dead. At the housewarming party, Jim's college friend, a police officer, arrives to tell him that Cindy's body was recovered from the beach. He also informs him that it is the tenth anniversary of the Hoffman deaths. Outside, the officer is overcome by a supernatural force which makes him shoot a partygoer before killing himself. Meanwhile, Pam gets into an argument with Debbie, and upon returning inside, is overcome by the supernatural force, which causes her to claw her own eyeballs out. Shortly after, the house's gardener is found stabbed to death by the pool. Debbie soon reveals herself to Jim as Deborah Hoffman, the daughter of Dr. Hoffman, returning to claim her home. It is also revealed she had an incestuous relationship with her father, and was responsible for the deaths of him and mother. Using her supernatural powers, she has been killing the boardinghouse tenants one by one, deeming them trespassers. Jim and Victoria bond together and engage in a psychic battle with Debbie, and ultimately are able to defeat her. A postscript reveals that the Hoffman residence burned to the ground the night of the party, and that Jim is now working professionally as a programmer, while Victoria is a successful singer. Debbie Hoffman's body is yet to be found.