On Christmas day in Grand Rapids, Michigan, businessman Jake VanDorn’s family hosts a celebration for their community in the Dutch Reformation Church. Sometime later, Jake’s daughter, Kristen, boards a bus for Bellflower, California, to attend the Youth Calvinist Convention, and, after seeing her off, Jake supervises work at his furniture factory. That Sunday, following church services, Jake receives a phone call, alerting him to Kristen’s disappearance during a field trip to Knott’s Berry Farm, and he flies to California with his brother-in-law, Wes DeJong. There, Wes’s daughter, Marsha, explains that Kristen was last seen with an older boy that she met at the park, and Detective Burrows suggests that Jake seek help outside of the police force. Jake and Wes meet private detective Andy Mast, who promises to find Kristen for a fee of $750 a week and asks Jake to go back to Grand Rapids to look for clues. At home, Jake is troubled by Kristen’s disappearance and Wes encourages him to hold faith. Jake soon receives a call from Mast, who has arrived in Grand Rapids. When Mast takes Jake to a pornographic movie theater to show him a hardcore film which features Kristen, Slave of Love, Jake cries and screams for Mast to turn off the projector. Mast explains the transient nature of the pornographic film industry and says he does not yet know Kristen’s whereabouts. Back in Los Angeles, Mast goes to the motel room set of a hardcore film to question his former colleague, Bill Ramada, but the man claims ignorance about Kristen. Four months later, Jake returns to California to search for Kristen, himself. Paying a surprise visit to Masts’s apartment, Jake discovers the detective seducing a porn star named Terry. After firing Mast and kicking him out of his own residence, Jake finds film stills from Slave of Love and begins an investigation of Los Angeles’s red light district. Outraged that no one will identify Kristen from the photographs, Jake decides to pose as a pornographic film producer, using the alias “Jake Devries,” and meets with Ramada and his partner, Kurt. Ramada turns down Jake’s offer to invest $50,000 but promises to introduce him to less established filmmakers who might be interested. Later, Jake posts a classified advertisement in a local newspaper for pornographic actors, hoping to meet Kristen’s co-star in Slave of Love . On the set of one of Ramada’s films, Jake meets a porn star named Niki. Back at his motel room, Jake is confronted by Wes, who has come from Grand Rapids with concern for his brother-in-law, but Jake asks him to leave. The next day, Jake holds casting calls for his mock film, and after a series of unsuccessful interviews, he meets Jim Sloane, a.k.a. Jism Jim, whom he identifies as the actor in the Slave of Love film stills. However, when Jake shows Jim a photograph and expresses interest in hiring Kristen, Jim argues that he will never work with her again because she injured him during sex and exhibited strange behaviors. Hitting Jim over the head with a lamp and dragging him into the shower, Jake forces the young man to report that Kristen worked with a man named Tod, who lives in San Diego. Although Jim knows nothing more about Kristen, he refers Jake to Niki, claiming that she is in contact with Tod. At a peep show parlor, Jake reunites with Niki and agrees to pay her $900 a week for her assistance. Meanwhile, Wes finds Mast at a restaurant and hires him to protect Jake. At a motel, Jake explains to Niki that Kristen is his daughter and his wife is deceased. The next day, as they wait at the airport for a flight to San Diego, Niki describes herself as a Venusian, a believer in Venus, the goddess of love, and claims that Jake’s Calvinism is negative and punitive. In San Diego, Niki tracks down a former client named Jim Rucker. She learns that Tod has been working with Ratan, a dangerous, sadomasochistic filmmaker, in Tijuana, Mexico, but is now residing in San Francisco. After Niki and Jake relocate to San Francisco, Niki sets up a meeting between Jake and Tod. As she and Jake wait at their motel, Niki accurately surmises that Jake’s wife is not really dead and suggests that Kristen became troubled when her mother left the family for a new life. Admitting that she is at the mercy of her pimp, Niki concludes that both she and Jake are victims of misfortune. Just then, Mast knocks on the motel room door and reports that the police are concerned about Jake’s safety. When Jake inquires about Ratan, Mast says the man is a threat and offers to work on the case. Later, at a meeting with Tod, Jake asks to meet Ratan. Although Tod feigns ignorance of Ratan, he agrees to let Jake view a sadomasochistic film they recently shot together in Mexico, featuring Kristen, in which Ratan murders two people. Returning to his motel room, Jake finds Mast quarreling with Niki, and when the detective leaves, Jake demands that Niki reveal Tod’s whereabouts. She refuses, concerned that Jake will abandon her once he finds his daughter, but when Jake hits her, she admits that Tod works at a bondage house in North Beach. Kissing Niki’s forehead, Jake promises not to forget her. As Jake leaves, Mast tries to stop him and calls the police. At the sadomasochistic club, Jake finds Tod and demands to know the location of Kristen and Ratan. As Tod smashes through the thin walls of the club’s dungeons, Jake gives chase and accosts him outside. Threatened by Jake’s aggression, Tod confesses that Ratan is at a nearby bar called El Matador. There, Jake confronts Ratan and Kristen, but Ratan pursues him with a knife. As Ratan runs from the bar, Mast arrives and shoots him in the back, killing him. Meanwhile, Kristen hides in the bar’s cellar and begs her father not to hurt her. Although Jake thinks Kristen was forced into pornography, she admits to willfully leaving her father and accuses Jake of disregarding her needs. When Kristen claims her new friends care more for her than Jake, her father tearfully confesses his inability to show love and promises to change. Despite Kristen’s demand that Jake leave, she decides to return to her father’s care. After Jake guides Kristen into a police car, he sees Niki in the crowd and offers to help her, but she walks away. When Jake asks Mast to look after Niki, the detective tells him to go home. Mast claims there is nothing Jake can do to rescue Niki because he does not belong in her world. Nodding in agreement, Jake joins his daughter in the police car.