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. Things get more weird when "Heidi" picks up a young prostitute named Dawn for a one-night stand, and who begins to visit Jackie for therapy sessions as well. Soon the line between reality and illusion blurs and it leads to Jackie finding out that her husband is cheating on her with her maid Paula which leads "Heidi" to plan a revenge with Dawn's help. Is Dawn really what she appears to be?