Roger Severs was a dead-beat. No job, no friends and living at home at 38, his only means of income was the occasional pocket money provided by his elderly parents. That was until they threatened to cut him off. Suddenly, Roger had a purpose... a deadly purpose. Robbie Coltrane reveals eight of the hardest, most complex and baffling murder cases ever to be investigated by British police. The focus of each programme is the trail of evidence: how it was discovered, what it meant and how it became critical to crack the case. With interviews from the lead investigators and forensic specialists, many speaking for the first time, Robbie reveals the astonishing twists and turns of often stranger-than-fiction cases. It is a record of the detectives’ art: using skill and determination to solve seemingly unsolvable cases – because the only difference between success and failure is critical evidence.