A troubled detective traces a few local murders to a renowned expert in hypnosis, only to find herself the doctor’s new target when she learns who is really pulling the killers’ strings.

Linda Mason is a renowned Forensic psychologist who is an expert at hypnosis. When her soon-to-be ex Michael dies suddenly while with his girlfriend Jennifer, Detectives Kenny James and Jack Riley feel that she takes the news a little too well. Michael was fighting for custody of their 8-year-old daughter Lizzy so that gives her motive. When his autopsy shows he was poisoned by arsenic, the detectives search his house and discover a bottle of the poison with Jennifer's fingerprints on it hidden in a cupboard and they arrest her for his murder.

Linda was Jennifer's therapist and advises her to take a lie detector test since she's innocent. The test concludes that Jennifer doesn't believe she killed Michael but she remains incarcerated.

Michael's parents, Robert and Brenda Mason, spend time with Lizzy and discover her nightmares growing worse. When they inform Linda, she uses hypnosis to try and calm Lizzy so she can sleep well. The in-laws decide go for custody, just as their son had done.

Kennie and Linda grow somewhat close. It's mainly Lizzy that draws Kennie in. She has always wanted a little girl but never had a stable relationship. Kennie uses the opportunity to question Linda about hypnosis, and dig deeper into the question of whether someone could be hypnotized to do something they normally wouldn't. Linda doesn't think that is possible, but Kennie remains skeptical.

After meeting with Lenny, a 17-year-old troubled teen at the rec center, Linda grows panicked that she will lose Lizzy to Michael's parents and calls someone, using the key word "Demelza". Shortly after, Lenny breaks into the couple's home and kills both. Kennie sees that as more than a coincidence and tries to convince Jack that Linda is the one behind the murders, killing anyone who threatens to take Lizzy away from her by hypnotizing others to do her dirty work. Jack begins to think that may be a possibility.

Kennie comes up with a plan to have another therapist hypnotize both Lenny and Jenifer to see if they can find evidence of what Linda did to them. While talking with Linda following a seminar, Kennie receives an urgent call from Jack that Lenny went ballistic early on in his session and escaped, possibly heading to Linda's house.

When Kennie and Linda arrive, they discover Jack has been killed by his own gun. Lenny is having a breakdown. The only way out for Linda is to hypnotize both and have Lenny kill her adversary so all threats to her losing Lizzy have been eliminated. After Kennie wins the fight and Linda is taken to prison, Lizzy moves in with Kennie while her mom becomes the patient in her new prison home.