Twenty-five years ago Britain was horrified by a murder story unfolding at 25 Cromwell Street in Gloucester, where Fred and Rose West had murdered and buried the remains of nine women and girls.

The Wests remain virtually unique in British criminal history as married serial killers and their cruelty beggars belief. Victims included their own daughter and the final death toll was twelve.

In advance of the anniversary of the start of the 1994 police investigation, Sir Trevor McDonald returns to Gloucester to ask the key questions: how were the Wests able to kill undetected in the middle of an English city for over twenty years; and to what extent was Rose West the driving force?

This powerful documentary includes a moving interview with one of the West children, in their first broadcast interview, revealing the appalling abuse that went on in 25 Cromwell St.