This is a modern detective story and it’s the story of a clue the world once knew but then forgot about or covered up. That clue is the key to the most notorious mystery in the history of crime. For more than 30 years it lay neglected a dusty sheet of paper buried in an old book shop. But now it’s the start of a trail that leads straight to the forgotten prime suspect in the white chapel murders of 1888. The victorian police had a vital clue, but it has been left until now for a suffolk police constable to discover. The story of Jack the ripper, has always been the stuff of melodrama, shrouded in fog and folklore, the ripper story is infested with bogus theories and suspects. Cutting through the fiction, this documentary attempts to focus on the forensic facts.