Episode 1

Sian O'Callaghan goes missing after a Friday night out in Swindon Old Town. As the family desperately waits for news, the police search for any clues to where she could be.

Episode 2

The hunt for Sian O'Callaghan continues as Det Supt Steve Fulcher and his team see suspects come and go with no leads to follow. Local woman Karen Edwards notices that she only lives a few doors away from the missing girl's mother, Elaine Pickford, but is only reminded of her own problems, having not seen her daughter Becky for several years. With things looking bleak for Wiltshire police, a brilliant piece of police work finally points Fulcher towards a definite suspect.

Episode 3

Detective Superintendent Steve Fulcher takes chief suspect Christopher Halliwell to a remote location to question him about Sian O'Callaghan's disappearance.

Episode 4

The families of Sian and Becky discover that, despite the confession of Christopher Halliwell, getting justice for their loved ones will not be straightforward.

Episode 5

Detective Superintendent Stephen Fulcher begins to witness the consequences of his actions in eliciting a confession from Christopher Halliwell for his career and his family.

Episode 6

When Wiltshire Police find a way to possibly bring Christopher Halliwell to court, Fulcher realises that he will have to come face to face with the man who ruined his career.