Forensic psychologists and behavioural experts examine some of the notorious criminal cases from the past 20 years in which the perpetrators appeared in front of the cameras with fake displays of grief. Aiming to show how such lies can be exposed through scientific methods, they look at the murders committed by Ian Huntley, Stuart Hazell and Mitchell Quy, Karen Matthews' plot to kidnap her own child, and Fadi Nasri, who hired a hitman to kill his wife. Narrated by Lesley Sharp