In 1985, Detective Inspector Gwyn Roberts was sent to a quiet Welsh seaside town to investigate an unusually threatening and vile anonymous letter, leading him to the home of mild-mannered clergymen, the Reverend Emyr Owen. What the police found in the unassuming house was shocking: dozens of pornographic magazines and books on black magic, cannibalism and surgery. But the most vital discovery of all was a series of photographs from which one thing became clear: the reverend was guilty of abusing and mutilating human bodies awaiting burial. To this day, with no similar offence ever recorded in legal history, it remains one of Britain’s most infamous criminal sprees.

The Rev, a true crime horror documentary, resurrects this gruesome yet fascinating story with interviews from police officers, psychiatrists and legal experts, who shed new light on the reverend’s disturbing actions and mentality. Interwoven are dramatic recreations that delve into Owen...