Description
American artist Mary Gilmore's van breaks down during a thunderstorm in rural Mexico. She finds an abandoned house nearby, occupied by a vagrant named Ben. He offers to spend the night there with her, to which she agrees. In the house, Mary reminisces about murdering a United States Embassy employee she seduced the night before and drinking his blood. Federal Bureau of Investigation inspector Otis Consgrove and Lieutenant Eduardo Pons begin investigating the murder, and subsequently uncover a series of similar crimes in which victims were drugged and drained of their blood.
Meanwhile in Mexico, Ben repairs Mary's van and the two spend the day at the beach. While Ben goes to buy fish, Mary drugs a middle-aged fisherman with coffee before stabbing him and drinking his blood. Back at Mary's home, she shows Ben a painting she completed of her father, whom she says died when she was young. That night in the morgue, a masked man breaks in to view the fisherman's body, stabbing a morgue employee to death before. Back at Mary's home, art dealers Greta and Arnold Jenson, view her artwork. After Mary's art show that night, Greta invites her to her home and attempts to seduce her. While she runs a bath for Mary, Mary drugs Greta's tequila. When Greta kisses her, Mary slashes her throat.
The following day, Cosgrove and Pons question Ben and Mary about Greta's murder, and accuse Ben when he fails to supply an alibi. Meanwhile, a young girl hitches a ride with the masked man who broke into the morgue. When he attacks her, she jumps from the car and flees into the woods, but is ultimately stabbed to death by the man, who reveals himself to be Mary's father. Upon reading of the girl's murder, Mary is unnerved as it seems another vampire is abroad. Mary's father begins to harass her, calling her home and attempting to run her over with his car.
Later at a party attended by Mary and Ben, Mary's father murders a young dancer and disguises himself in his costume. He manages to kidnap Mary from the party, but she flees to a nearby cemetery where her father murders a gravedigger before escaping. Convinced Ben is responsible, Cosgrove and Pons stake out Mary's house. Mary and Ben leave, and are followed by her father in a separate car. As they enter the woods, Mary drugs Ben's coffee before dragging his unconscious body into the woods. Mary's father attempts to force Cosgrove's car off the road, resulting in a collision. As Cosgrove attempts to exit his car, Mary's father stabs him to death.
Mary, about to slash Ben's throat, stops when she hears the wreckage, and witnesses her father feeding on Cosgrove. He explains to Mary that his hunger has driven him mad, and removes his mask to show half his face has rotted away. Meanwhile, Ben regains consciousness, and attacks Mary's father, ultimately shooting him with Cosgrove's gun. Mary begins drinking her father's blood before stabbing Ben and feeding on him. Later, at the police station, Pons accepts Mary's account of the masked killer, her father, being responsible for Ben's death. She tells him she plans to leave Mexico and travel before driving away in her van.
