American artist Mary Gilmore [Cristina Ferrare]'s van breaks down during a thunderstorm in rural Mexico. She discovers an abandoned house nearby, inhabited by a vagrant named Ben [David Young], who offers to spend the night there with her, and she agrees. Inside, Mary quietly recalls a dark secret from her past: she seduced a United States Embassy employee and drank his blood. This brutal memory sets a chilling tone as FBI inspector Otis Cosgrove [Arthur Hansel] and Lieutenant Eduardo Pons [Enrique Lucero] begin to investigate the murder, soon uncovering a string 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, a brief respite that contrasts with the looming danger. Mary drugs a middle‑aged fisherman with coffee before stabbing him and drinking his blood, a sinister repetition of her earlier confession. Back at her home, she reveals a painting of her father, José Ángel Espinosa 'Ferrusquilla', and the quiet moment is pierced by another grim note of her lineage. That night in the morgue, a masked man breaks in to view the fisherman's body and stabs a morgue attendant, Jorge Humberto Robles, adding a new layer of menace to the unfolding mystery. Not long after, Greta and Arnold Jenson—art dealers who champion Mary’s work—arrive and witness her latest creations. Greta, drawn to Mary, invites her to her home, where Greta’s attempts at seduction give way to a deadly confrontation: while preparing a bath, Mary drugs Greta’s tequila, and when Greta kisses her, Mary delivers a fatal stab to Greta’s throat.
The next day, Cosgrove and Pons question Ben and Mary about Greta’s murder and publicly cast suspicion on Ben when he cannot provide a solid alibi. In the wake of Greta’s death, a young girl [Susana Kamini] hitches a ride with the masked man who broke into the morgue; she is attacked, escapes into the woods, and is ultimately stabbed to death by the man, who is revealed to be Mary’s father [Ferrusquilla]. Reading of the girl’s murder unsettles Mary, who senses the presence of another vampire on the loose. Her father begins to harass her, calling, and even attempting to run her over with his car, amplifying the sense of threat hanging over her.
Later, at a party Mary attends with Ben, her father murders a young dancer and disguises himself in the dancer’s costume. He makes a failed attempt to kidnap Mary from the party, forcing her to flee to a nearby cemetery where a gravedigger [Reynaldo Rivera] is murdered in front of her eyes. Cosgrove and Pons stake out Mary’s house, convinced the killer is close, while Mary and Ben leave together, only to be followed by her father in a separate car. In a tense sequence in the woods, Mary drugs Ben’s coffee and drags his unconscious body deeper into the trees, while her father drives toward Cosgrove’s car, triggering a wreck. As Cosgrove tries to exit his vehicle, Mary’s father stabs him to death, a brutal revelation that confirms the killer’s true identity and purpose.
The climax unfolds with a stark confession from the father: his hunger has driven him mad, and he unveils a rotted half of his face, explaining that Mary’s fate—being a vampire—is sealed, and the only cure is death. Ben regains consciousness, attacks Mary’s father, and is ultimately shot with Cosgrove’s gun. Mary drinks her father’s blood and then fatally stabs Ben, feeding on him as the night closes in. In the aftermath, Pons accepts Mary’s account of the masked killer, her father, and she declares that she intends to leave Mexico and travel, driving away in her van as the story ends with an uneasy, blood‑streaked calm.
