Edgar Lynden is a prison hospital doctor who conducts some unauthorized and certainly unethical medical experiments in company with his ruthless paramour, Dr. Patricia Morella. He has a twisted relationship with her, which becomes macabre when, as she is comatose and dying from a rare degenerative disease, he implants an embryo cloned from her DNA into her womb. The embryo grows up to become Sarah Lynden, Dr. Morella's spitting image, who has psychic powers and an exaggerated form of her mother's ruthlessness. From childhood onward, anyone who is inconvenient to her has died or suffered horribly. Eventually, her adoptive father realizes the extent of his errors.