Across the UK, there are hundreds of thousands of unsolved sexual offences lying dormant in police archives. Some go back decades. One remarkable police unit is trying to change that by harnessing the power of modern DNA techniques. Can they find the men responsible for the kidnap and serious sexual assault of two schoolgirls in 2002 and the rape of a teenage boy in 1983?

Across the UK, there are hundreds of thousands of unsolved sexual offences lying dormant in police archives. Some go back decades. One remarkable police unit is trying to change that by harnessing the power of modern DNA techniques. Can they catch a rapist who has gone unpunished for nearly 30 years? And have they caught the man who kidnapped and sexually assaulted two schoolgirls in 2002?