In episode 3 'The Trial', the police extended their search for bodies beyond Cromwell Street and uncovered evidence suggesting that Rose West was more involved in the murders than previously suspected, indicating her deeper complicity in the crimes.

Fred West is shown in the episode as being strikingly matter-of-fact during police interrogations, calmly confessing to 12 murders and helping police locate the bodies at 25 Cromwell Street, known as the 'house of horrors'.

Caroline Owens, a former nanny to the West children, is a key witness in the trial; she recounts how she was kidnapped and sexually assaulted by Fred and Rose West but managed to escape, and her interviews are featured in the documentary.

The episode reveals that the Wests' children, including Louise and Anna Marie, were victims of abuse and provided statements to police; however, they later declined to testify in court out of fear of Rose's retaliation, which affected the prosecution's case.

During the trial, Rose West is shown denying all involvement in the murders and maintaining her innocence, contrasting with Fred's confessions; however, evidence and police suspicions suggest she was deeply involved.