Fact1: Scotty Parker is seeking room for fall semester at last-minute, Fact2: Doris and Peter walk near house, Fact3: Scotty returns to room with Jack, Fact4: hidden staircase travels along house 's air ducts eventually leading to room located off main attic space, Fact5: Mason chastises mother for having taken in boarders at house
Output: Scotty Parker, a college student in Southern California, is seeking a room for the fall semester at the lastminute. She is directed to a boarding house run by the standoffish Mrs. Engels; a Victorian mansion on a cliffside overlooking the Pacific Ocean. Mrs. Engels lives in the house along with her teenage son, Mason, and several other college students, including Doris, Peter, and Jack. The four students become friends, and decide to go on a double date together. Afterward, Doris and Peter walk along the beach near the house. Peter, drunk, makes unwanted advances on her, and Doris leaves him on the beach. He falls unconscious, and is awakened by an unseen assailant who stabs him to death with a butcher knife. Lieutenant McGiver and Sergeant Manny Rusin are assigned to investigate Peters murder, and Lt. McGiver grows suspicious of the Mrs. Engels and her son. One afternoon, Scotty and Doris meet in the basement laundry room, where Doris tells her she is planning on moving after what happened to Peter. Scotty returns to her room with Jack, and the two begin to have sex. Meanwhile, in the basement, a woman bursts out of a hidden door, stabbing Doris numerous times in the head and chest. The woman flees through the secret door, which opens to a hidden staircase that travels along the houses air ducts, eventually leading to a room located off the main attic space. Scotty goes downstairs to get her laundry, where she finds a pool of blood, and Doris gone. She discovers the secret door, and ascends the staircase. At the top, she finds a narrow hallway with a door at the end. She attempts to open it, and is attacked by the woman, who pulls her inside. The commotion alarms Mrs. Engels, who enters the room from an access door in the attic and intervenes. Mrs. Engels reveals that the woman, Victoria, is her daughter. Mason chastises his mother for having taken in boarders at the house, knowing of Victorias violent outbursts. Mrs. Engels then reveals to Mason that Victoria is in fact his mother: After a failed suicide attempt, she gave birth to him, but was left mute and homicidal after undergoing a botched lobotomy at a psychiatric hospital. Meanwhile, Jack searches for Scotty throughout the house, but is unable to find her. He is confronted by Mason downstairs, who knocks him unconscious. At the police station, Sgt. Rusin uncovers a file on Victorias past and determines she has been living in the Engels home after being taken out of the psychiatrist hospital; he and Lt. McGiver promptly leave to go to the boarding house. Meanwhile, with Scotty bound and gagged in a closet, Mrs. Engels attempts to console the childlike Victoria. Mason obtains a gun from his bedroom and returns to the attic, attempting to kill Victoria. In a struggle, he inadvertently shoots Mrs. Engels through the chest, killing her. With his back turned, Victoria approaches Mason. He turns around, and she stares at him blankly, moving closer with a knife. Cornered against a window, he shoots her, and then shoots himself in the head. Scotty manages to free herself, but finds Victoria has survived the gunshot; she attacks Scotty with the knife. Jack awakens just as Lt. McGiver and Sgt. Rusin arrive at the house. They enter the attic and find Victoria collapsed with a knife in her stomach. Jack consoles Scotty as Victoria dies on the floor.