Robbie Coltrane tells the true story of when the Cambridgeshire police arrive to discover a man's body has been burnt beyond recognition. All they find is the state of the victim plus a charred torn up letter, could this be enough to find the killer? 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.