One night, single mother Carla Moran is violently raped in her Los Angeles
bungalow by an invisible assailant. A subsequent episode of
poltergeist activity causes her to flee with her children to the home of her best friend Cindy Nash. They return to Carla's home and the following day, Carla is nearly killed when her car mysteriously goes out of control in traffic. Urged by Cindy to see a psychiatrist, Carla meets with Dr. Sneiderman and tentatively agrees to undergo therapy. A subsequent attack in her bathroom leaves bite marks and bruises, which Carla shows to Dr. Sneiderman, who believes they are self-inflicted despite being in places impossible for her to reach. Sneiderman drives Carla home and meets her children. She explains to him that she suffered a variety of traumas in her childhood and adolescence, including
sexual molestation, teenage pregnancy, and the violent death of her first husband. Dr. Sneiderman believes her apparent paranormal experiences are delusions resulting from her past psychological trauma but agrees to keep an open mind at her request. Shortly after Sneiderman leaves, Carla is attacked again, this time in front of her children. Her son tries to intervene, but he is hit by electrical discharges and his wrist is broken. Carla attends a staff meeting chaired by Sneiderman's colleague, Dr. Weber. As soon as she leaves, Weber shares his belief that the experiences of the Moran household are the output of a
mass delusion arising from Carla's damaged psyche,
sexual frustration and propensity to
masturbate. That night, Carla is tricked by the entity into having an orgasm while she sleeps by appearing to stimulate her nipples. The next day, Sneiderman urges Carla to commit herself to a psychiatric hospital for observation, but she refuses and becomes angry when Sneiderman goes so far as to suggest she has
incestuous feelings for her son. After Cindy witnesses an attack, the two discuss possible supernatural causes. While visiting a local bookstore, Carla happens to meet two
parapsychologists, whom she convinces to visit her home. Initially skeptical, they witness several paranormal events and agree to study the home under the supervision of their team leader, Dr. Cooley. During their study, Sneiderman arrives and tries to convince Carla that the manifestation is in her mind, but she dismisses him. Reassured that her case is taken seriously, Carla begins to relax. Her boyfriend, Jerry Anderson, visits one night and witnesses Carla being held down on the bed by the entity while being raped and noticeably fondled by invisible fingers. Confused and horrified, he attempts to fight off the entity. Hearing the commotion, Carla's son enters the room and believes that Jerry is harming her, prompting him to attack Jerry. Later at the hospital, Jerry is so troubled by the experience that he ends their relationship. Desperate for a solution, Carla agrees to participate in an elaborate experiment carried out by Cooley's team. A full mock-up of her home is created to lure the entity into a trap and freeze it with liquid helium. Before the experiment begins, Sneiderman tries to convince Carla to leave, confirming an unorthodox personal interest in her predicament. The entity arrives but unexpectedly takes control of the helium jets, using them against Carla. She defiantly stands up to it, stating that it may kill her, but it will never have her. At this precise point, the tanks explode and flood the premises with liquid helium. Sneiderman rushes in just in time to save her. As everyone watches, they realize that the entity is far bigger than anyone imagined and has been trapped in a huge mass of ice. It breaks free and vanishes almost immediately, but Sneiderman realizes that Carla has been telling the truth. Dr. Cooley believes that, despite the destruction of the ice block, she has a valuable witness in Dr. Weber. Much to her chagrin, however, Weber
decides to take refuge in the belief that he did not witness anything. Carla returns to her house the next day. The front door slams by itself and she is greeted menacingly by a disembodied
demonic voice which says, "Welcome home,
cunt." She calmly opens the door, exits the house, gets in a car with her family and leaves. A closing intertitle verifies that Carla and her family have moved to Texas. Carla still experiences attacks from the entity, although they have lessened in frequency and severity. ==Cast==