In July 2014, police in Manchester arrested a 34-year-old man on suspicion of filming himself raping a child. In the video, the face of the perpetrator was hidden but his hands were visible. Detectives felt they had the right suspect in custody, but didn't yet have enough evidence to secure a conviction. With time running out, they turned to forensic anthropologist, Professor Sue Black, an expert in the identification of unique anatomical features, including hands.