Lynn Webster is raped by her father and retaliates by stabbing him to death. When Lynn swears that her father is still alive, she is committed to the California State Hospital in Camarillo, where she endures shock therapy. When a nurse undresses to make love with a doctor, Lynn steals the uniform and escapes in a stolen Volkswagen Beetle. Meanwhile, a pig farmer and café owner named Zambrini drags a dead body into a barn, explaining aloud that his swine have a taste for human flesh. Later that night, Lynn pulls up to Zambrini’s deserted café and hears bellowing pigs. As Zambrini approaches, Lynn says that she is responding to his help wanted sign and he shows her to her quarters, where she discovers a switchblade in the bathroom vanity. Meanwhile, a neighbor named Miss Macy complains to Sheriff Dan Cole about Zambrini’s noisy pigs and reports that he feeds them human corpses from the cemetery, but Dan informs her that dead people do not have civil rights. The next day at the café, Lynn learns from a customer named Ben that Zambrini is known for recruiting pretty waitresses, then feeding the girls to his pigs. Warning Lynn to leave town, Ben explains that Zambrini was a circus performer who fell 500 feet from a platform and was presumed dead. Although Zambrini recovered, he is mentally disturbed. As Ben leaves, Zambrini interrogates Lynn about the conversation, but she remains unfazed. Just then, Sheriff Dan arrives, warns Zambrini about Miss Macy’s accusations, and asks Zambrini to keep his pigs enclosed at night. The sheriff has discovered that Lynn’s Beetle is a stolen vehicle, but Zambrini coaxes him into overlooking the girl’s trespasses. Sometime later, Ben discovers a nurse’s uniform in a field and suspects it belongs to Lynn. On a date that night, Ben forces himself on Lynn and she runs away with Sheriff Dan, who drives her back to the café and asks if she is related to Zambrini. The next day at work, Ben boasts that he made love to Lynn. Despite his tall tale, Ben is later seduced by Lynn, who apologizes for being cold toward him the previous evening. However, as they climb under the sheets, Lynn murders him with Zambrini’s switchblade. Lynn cries that she is innocent as Zambrini cleans blood from her face, tucks her into bed, and lulls her to sleep. Zambrini then drags Ben’s body into the barn, hacks it into pieces, and feeds the pigs. In the morning, Lynn phones her dead father and hallucinates that he is unable to take the call. Meanwhile, Miss Macy reports to Sheriff Dan that she heard Zambrini’s pigs squeal incessantly the night of Ben’s disappearance. She claims that Zambrini’s victims transform into pigs, themselves, after they are fed to the swine. Back at the café, Sheriff Dan questions Zambrini and the men find Ben’s dog guarding the pigpen. Returning to Miss Macy’s house, Sheriff Dan reports that he could find no evidence against Zambrini. The town doctor, who confirms Miss Macy’s physical and mental health, explains that ancient Egyptian mythology prophesized humans turning into pigs after death, but Sheriff Dan remains unconvinced. When he later questions Lynn about Ben and invites her to join him for a weekend out of town, Ben’s friends search for their missing companion and beat Zambrini outside his barn. Zambrini kills Ben’s dog in retaliation and Sheriff Dan orders Ben’s friends to end their vigilante crusade. Sometime later, Jess Winter, a representative from the California State Hospital, arrives in town to search for Lynn and is directed to the café. There, Jess tells Lynn that she is missed at the hospital. Lynn is surprised that her return is welcome and agrees to leave with Jess, but Zambrini asks her to stay and she stabs Jess in the back. As she cleans the knife, Sheriff Dan arrives at the café, but is called away before he sees Jess’s body. While Sheriff Dan thwarts another attack on Zambrini by Ben’s friends, Zambrini feeds Jess to his pigs. Back at the police station, Sheriff Dan receives word of Jess’s disappearance and learns that Lynn is an escaped mental patient. He then calls Zambrini to warn him about Lynn. Zambrini encourages Lynn to escape, but she demands to know her father’s whereabouts before she leaves. When Zambrini announces that Lynn’s father is dead, she calls him a liar and stabs him in the back. As Sheriff Dan rushes to the café, Lynn again phones her father to declare her love. Before the sheriff arrives, Lynn hacks Zambrini into pieces, feeds the pigs, and removes her clothes, including an Egyptian ankh necklace. Later, Sheriff Dan files a report that states Lynn was devoured by the swine. While the sheriff mourns her loss, Lynn drives out of town in the stolen Beetle and picks up an older gentleman hitchhiker who reminds her of her father.