Marcus is a twelve-year-old schoolboy whose mother has recently died, leaving it up to his wealthy father Paul to look after him. He takes a sexual interest in his stepmother Elise. She notices his abnormal behaviour and investigates by visiting his school after discovering a torn-up letter from his headmaster. Elise is shocked by her findings. She becomes increasingly disturbed and wonders if Marcus is to blame for his mother's death. She enlists the help of psychiatrist Dr Viorne to find answers.