The Investigator: A British Crime Story

Teenager Louise Kay has been missing since June 1988 in a case that has baffled police and left her family desperate for answers.

Williams-Thomas's investigation sends him on the trail of the prime suspect in her murder, convicted killer Peter Tobin, who was living nearby at the time. As he delves deeper into the case he discovers a series of other missing women and unsolved murder cases who could also be the undetected victims of a serial killer.

In the second episode, Williams-Thomas investigates the notorious murders of Anna Kenny, Agnes Cooney and Hilda McAuley - who were all abducted and brutally killed in similar circumstances within four months of each other in Glasgow in 1977.

He investigates the prime suspect, convicted killer Angus Sinclair, and the evidence suggesting he is responsible for the unsolved murders.

Mark Williams-Thomas's investigation uncovers another Glasgow murder that bears all the hallmarks of suspected serial killer Angus Sinclair. There is just one problem - unlike the murders of Anna Kenny, Agnes Cooney and Hilda McAuley, this crime has already been solved. A week after 37-year-old baker Frances Barker's body was discovered, lorry driver Thomas Ross Young was arrested, and was subsequently jailed for life. The investigator tries to establish whether the police got the wrong man - or if there could be another explanation. Last in the series.