A chemistry-obsessed teenager becomes fascinated by poisons and uses his dysfunctional family as subjects in a series of bizarre experiments. When his schemes are uncovered, he is committed to an asylum, where he tries to convince a respected psychiatrist he is not a danger to society. Once he rejoins the outside world, the temptation to return to his old tricks proves unbearable. Black comedy based on a true story, starring Hugh O'Conor, Roger Lloyd Pack and Antony Sher.

Graham Young is a teenage misfit living in suburban London in the 1960s. He hates his stepmother but loves chemistry, and the two impulses unite in a wicked plot to slowly poison her. After she dies, he's found guilty and sent to a psychiatric hospital, where an idealistic doctor thinks he can be cured.