Part one of two. Drama telling the story of how serial killers Fred and Rosemary West were brought to justice. In 1994 the life of Gloucestershire voluntary worker Janet Leach is turned upside down when she is asked by police to sit in on interviews as an independent safeguard on behalf of a man they have arrested. Within minutes he makes a shocking confession of murder. From then on she is drawn into the centre of the investigation and a complex personal relationship with West, who tells her information about other victims that she cannot pass on to the authorities because of her obligation of confidentiality to him. Starring Emily Watson, Dominic West, Monica Dolan and Robert Glenister.