Dee Stanton announces to her fifteen year-old son Jamie that she is seeing his English teacher Dominic Milne. When Dominic proposes to her, Dee is forced to tell him her big secret- that she was married to Paul Barker who, unknown to her, led a secret life as a serial killer and was convicted for having strangled several women. She has told Jamie that his father was a pilot who died in an accident. However, Jamie is eavesdropping on them talking and hears everything. Jamie demands to go and see his father in jail and Dee reluctantly agrees to this. Barker immediately begins weaving a seductive spell on Jamie's mind. Meanwhile, Jamie has been following schoolgirl Morag Tait to the extent that she has had to complain about him. Morag is then found strangled in the woods. Police suspect Jamie who cannot account for what he was doing at the time, until Dee stands up to lie and create an alibi for him. The police then suspect Dominic. Morag was seen in Dominic's arms just before she disappeared and wrote in her now missing diary and told several friends that she was having an affair with him. Now Dee cannot be sure whether her son has started following in his father's footsteps or whether the man who has proposed to her is a murderer, too.