Nathan Wyeth finds himself hopelessly in love with a woman named Sheila, not realizing they are both vampires. When she disappears without a trace, he is joined by his friend Ronnie, trying to find some meaning in her mysterious existence. Ronnie falls in love with Nathan, not realizing he is a vampire. Lieutenant Joe Mace, investigating the violent murder of Ronnie's husband, runs into government-funded groups bent on controlling vampires, conducting a program to 'resocialize' them by medical treatment. When Nathan relapes from his treatments he is taken into custody by the vampire control project. Ronnie joins Mace to search for Nathan. After escapes and rejoins Sheila, Nathan is hunted by 'feral' vampires as well as the control project police. "You must kill her," says the vampire Little Eva, "Or we will." Confused by his love for both Ronnie and Sheila he decides to join Ronnie and disappear. However, they are captured by the vampires and sentenced to death in a mock trial.