Serial killer Frank Zito watches a couple sleeping on the beach. When the girl awakens and asks her boyfriend to collect wood to rebuild the fire, Frank sneaks behind her and slits her throat. When the boyfriend returns, Frank kills him, too. Later, Frank awakens in his bed, lying next to a mannequin with blood dripping down her face. Mannequins, mannequin body parts, and dolls fill the room. As Frank dresses, he fingers several scars on his chest. He roams New York City streets and engages the services of a prostitute, but in the hotel room, he asks her not to undress. As they lie on the bed, she kisses him and he strangles her. Frank vomits in the bathroom, cries, and wonders aloud why he killed her. Then he returns to the room and scalps the prostitute. Later, Frank brings a mannequin in a large plastic bag to his home. Inside, he asks the mannequin lying on the bed if she missed him, and then moves her to a corner of the room. As Frank unwraps the new mannequin, he mumbles aloud that he should not have gone out, and a voice inside his head responds that the killings must stop. As Frank and the voice in his head converse, he takes the prostitute’s clothes from the bag, then nails her bloody scalp to the mannequin’s head. The voice in his head is frightened that Frank will be caught, but insists that if he obeys the voice, “they” will not take him away. Frank reads the newspaper’s headline, which reports, “Maniac mutilates couple at beach.” He hides a rifle, bullets, and knives in a music case, then leaves, promising the mannequins to return soon. He drives to a discotheque, notices a couple leaving, and follows them to a park near the river. As the lovers kiss, the girl sees Frank peering in the window, but Frank quickly hides and the man does not see him. The girl wants to go home and the man reluctantly agrees, but when he turns on the headlights, Frank appears in front of them, wielding a rifle. Frank jumps on the car’s hood and fires pointblank at the man’s head. The girl ducks, but Frank kills her, too. Later, after Frank watches television coverage of the slayings, he turns to his newest mannequin, her head wrapped in black material, and promises he will not let anyone take her from him. Handcuffing himself to the mannequin, Frank snuggles close to her. At a park the next day, two mothers converse, paying scant attention to their children, while a beautiful photographer, Anna D’Antoni, takes pictures nearby. As the children ride bicycles into the park, Anna photographs Frank stopping the little girl and warning her to be careful. Frank notices Anna and, as she continues photographing the park, he wanders by her equipment bag, reading her name and address on the label. That night, a nurse waiting for a ride home sees a newspaper headline reporting that the “maniac” has slaughtered two more victims. Her ride is late, so the nurse heads toward the subway. When Frank trails her, she suspects she is being followed, then fumbles with her change at the entrance. Seeing Frank, she rushes inside the station, but misses her train. The station’s exits are locked, so the nurse hides in a bathroom stall, but Frank finds her, stabs her with a sword, and later nails her bloody scalp to yet another mannequin. Later, Anna develops the photograph of Frank and he arrives at her home, nicely dressed, claiming he noticed her taking his picture in the park. As he admires her current series of photographs of women, Anna says she likes to make women look beautiful. However, Frank counters that the women are already beautiful, and photographs allow viewers to possess that beauty forever. Frank claims to be an artist and asks Anna to go to dinner with him, admitting that she is the most beautiful woman he has seen since his mother. He also shares that his mother died in an automobile accident when he was younger. Anna ends their dinner early because she must return to work, but suggests they meet again. When Frank complains she will probably cancel future plans, she invites him to her photography exhibit that Thursday. Later, as Anna photographs three models at her studio, Frank arrives unexpectedly. When Anna takes a break, Frank presents her with a stuffed animal, and she introduces him to a model named Rita. Anna asks Rita to take off her gold necklace because it is reflecting too much light and, as they return to work, Frank steals the necklace and leaves. When Rita goes home, Frank arrives to return the necklace and surreptitiously unlocks her door. A short time later, Frank attacks Rita, revealing that he has confused the girl for his deceased mother. He scolds his imaginary mother for abandoning him while engaged with many sexual partners, but insists that he always knew he would find her. As Frank stabs Rita, he claims he is not killing her, but keeping her forever. He removes her scalp, telling “Mommy” she is staying home with him tonight. Days later, Frank asks Anna to go on a second date and she accepts, thanking him for attending Rita’s funeral. On their date, he suggests they place a Christmas wreath at his mother’s headstone. When they reach Carmen Zito’s grave, Frank cries that his head hurts and insists “that Rita knew.” Scared, Anna runs away and hides behind a gravestone. As Frank nears, she hits him with a shovel, slicing his arm and knocking him down. Anna runs away while Franks hears a voice insisting “Mommy” has to punish him. When Frank kneels again at his mother’s grave, her corpse reaches from the ground to embrace him. Screaming, he stumbles out of the cemetery and returns to his apartment, where he imagines his mother on the bed. Frank lies down, looks at the blood-soaked mannequins and cries for his mother. When he looks back at the mannequins, he sees they have morphed into his victims. The women grab weapons and attack, ripping his head off. The next morning, two officers arrive at Frank’s apartment to find he has apparently committed suicide by stabbing himself in the stomach. The officers note the bloody mannequins sitting by the table, and then leave, closing the door behind them. On the bed, Frank’s eyes open.