Dr. Jackie Stevenson is a Los Angeles based therapist and scientist who tries to invent a serum to separate the pure from the lustful side of the female psychosis. After she has an unsuccessful experiment with a female client named Martine, which drove her patient to insanity and to a mental hospital, Jackie tries part of the serum on herself and becomes her lustful alter ego Heidi Hyde; a voracious lesbian who prowls the streets of L.A. after dark looking for carnal pleasures.