Tracie Andrews purportedly witnesses the murder of her boyfriend Lee Harvey in a country lane in December 1996, but all is not as it seems.

When the body of EastEnders actress Gemma McCluskie is discovered in Regent's Canal in March 2012, dogged detective work eventually leads the police to her brother Tony.

When Special Investigating Officer Steve Wilkins is shocked at a series of unsolved crimes in his hometown, he is given permission to launch a new operation to review all the evidence.

A dangerous killer is on the loose and detectives need to act fast when the bodies of two men are found stabbed to death in neighbouring flats in Derby.

When a body is found by a river in Cumbria that is 70 miles from home, eight years of tireless investigative work pass until one vital piece of evidence blows the case wide open.

As the documentary series continues, Tony Blockley and his team find a perplexing murder scene and launch an inquest.

When a woman's body is found at a pumping station in Hull, senior investigating officer Paul Davison and his team are tasked with identifying her and how she was murdered.