After his wife is accidently electrocuted by a faulty coffee maker, Minneapolis, Minnesota-based psychologist Cal Jamison moves to New York City with his eight-year-old son, Chris, and obtains a job as a police psychologist. Lieutenant Sean McTaggert calls Cal in to study undercover policeman Tom Lopez, who has been admitted to the psychiatric unit at Bellevue Hospital. Lopez was investigating the disappearance of children in Spanish Harlem, when he had a psychotic breakdown during the investigation of a murder in which a child appeared to have been a religious sacrifice. The child’s body was brutally butchered, but cut with precision, and surrounded by religious paraphernalia. Strapped into a wheelchair, Lopez talks gibberish. He says he passed out, and when he regained consciousness, he found the boy’s body, and fears someone is going to kill him. Later, Lopez attacks an orderly and escapes. McTaggert informs Cal that Lopez practices a religion known as “Santeria.” Originating in Africa, Santeria predates Christianity by over 1,000 years. Slaves brought it to the Caribbean, but when their owners forced Christianity on them, they hid their religion and substituted their gods for Christian saints. Cal visits landlady/handywoman Jessica Halliday, who lives in a brownstone apartment building across the street. They get along well, and when they have sex, it is Cal’s first time since his wife’s death and Jessica’s first since her divorce a year earlier. Later, when young Chris accidently breaks a ceramic pot Jessica gave them as a housewarming gift, they find her earring wrapped in Tom Lopez’s handkerchief, along with other trinkets. Their maid, Carmen Ruiz, who practices Santeria, put the items together in the pot as a way of bringing Cal and Jessica together. Later, Cal finds religious candles, necklaces, and other items that Carmen put in Chris’s room for protection. Cal throws them out, but later, when Chris is sick with a fever, Carmen chants over his body. After finding more religious trinkets, Cal fires her. A feverish Tom Lopez telephones Cal, asking to meet him at a diner in Spanish Harlem. Arriving at the diner early, Tom orders hot water, mixes herbs in his cup, and drinks the concoction. He becomes ill and stabs himself in the stomach. By the time Cal arrives, Tom is dead. McTaggert and Cal visit a neighborhood youth center in Spanish Harlem to question the director, Oscar Sezine, who has written a book about Santeria. Oscar tells them the center’s doors are open to anyone who is troubled, and reports that Tom Lopez was a volunteer who taught boxing to the children. McTaggert reports that another young boy has been found murdered aboard a river barge in what appears to be a religious sacrifice. Oscar confirms that the boy came to the center, but assures Cal that Santeria is a force for good. He is afraid that society’s misunderstandings about the religion will create problems. Cal takes Jessica to a fundraiser, where he meets Donald Calder, chairman of the board of Oscar Sezine’s youth center. Jessica overhears Calder tell Oscar that he will handle everything connected with the murder investigation. While Jessica is in the restroom, a black man puts powder in her compact, which she later uses to touch up her makeup. A few minutes later, the same man performs a Caribbean ritual dance that puts many guests, including Jessica, into a trance. Cal pushes the man away and rushes Jessica out of the room. Family friends Dennis and Kate Maslow take Chris to their lake house in New Jersey to get him out of harm’s way, and Cal promises to join them on the weekend. McTaggert informs him they are curtailing the investigation because Tom Lopez was the murderer, but Cal believes the policeman was innocent. He asks Oscar Sezine about a seashell necklace his son found, which Carmen had then taken away from him. Oscar insists the necklace is not connected to Santeria, but is rather a part of “Blujeria,” black magic. Oscar tells him that in times of disaster, a tribe would sacrifice three children to ward off the threat. Examining written details of the ritual sacrifice, Cal realizes that they describe how the recent victims were murdered. Oscar performs a special protection ritual for Chris. Jessica develops a pimple in the spot where she touched up her makeup, and it soon develops into a large bruise. She becomes very ill, and Cal takes her to the hospital. When he visits Lt. McTaggert’s apartment, he finds the lieutenant rambling in the same paranoid way as Tom Lopez had done. He shows Cal an eight-year-old autopsy report revealing that Donald Calder killed his young son in a ritual sacrifice. Lt. McTaggert tries to shoot himself, but Cal wrestles the weapon away from him. After Cal leaves, McTaggert takes another gun and shoots himself in the head. Cal gives the autopsy report about Calder’s son to his friend, lawyer Marty Wertheimer, for safekeeping. Marty drives Cal to the Maslows’s lake house. Dennis Maslow tells Cal that while he and Kate were doing fieldwork in the Sudan in 1946, they became friends with members of the local tribe. The area was in the middle of an extreme drought, and when their young son became deathly ill, a tribesman asked the Maslows to sacrifice their son to help end the drought, and they did so. At that moment, Donald Calder and several others enter the room and talk about the power they feel after joining black magic worshippers. Dennis Maslow informs Cal that Chris was chosen to be sacrificed when he found the seashell necklace. They invite Cal to join with them and sacrifice his son, but Cal refuses. He runs upstairs to get Chris, but the boy is not there. Calder and his men drug Cal and take him to a warehouse that has been prepared for the sacrifice. Chris lies on a table, sedated. Cal is given the sacrificial knife, but rather than stab his son, Cal plunges it into Dennis Maslow. Meanwhile, a suspicious Marty Wertheimer follows them to the warehouse and opens fire on Calder’s men. Grabbing the unconscious Chris, Calder dashes away, but Cal stabs him and carries his son to safety. However, the black man from the fundraiser confronts Cal and tries to choke him on a scaffold. Chris takes off his seashell necklace and lures the attacker toward him, causing the man to fall to his death. Cal and Chris run to safety. Later, Cal and Jessica marry, and the family goes on a vacation.