|Hugh O'Conor||Graham Young|
|Antony Sher||Dr. Ernest Zeigler|
|Roger Lloyd Pack||Fred|
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. Upon release, Graham finds a job, but struggles to fight back his old urges for murder. The film is based on the true story of the ''Teacup Murderer.''