When the full moon rises, Marlo undergoes a bizarre transformation that turns his werewolf-vampire hybrid form into that of a girl. This perplexes him, and his parents enlist the aid of their friend, Dr. Vincent, to investigate the issue. Marlo is hesitant to reveal this unusual gender-shift anomaly to Dr. Vincent's son, the notorious vampire Lothario, David.
Despite his attempts to keep the matter hidden, the truth eventually surfaces, and Marlo is confronted with a troublesome dilemma - David's enduring romantic interest in him. The parents propose an audacious solution if a remedy cannot be found - Marlo and David should wed.
