The gripping true story of how Detective Superintendent Julie Mackay brought Melanie Road's murderer to justice.

BATH, 1984

Jean Road, a 49-year-old mother of three, awakens to news that her daughter Melanie has been murdered in a nearby street as she walked home from a club in the early hours.

Britain's biggest manhunt begins. A trail of blood is found leading away from the scene. It's a rare blood type. But despite a year-long inquiry and 94 arrests, the case is wound down. No one is charged with Melanie's murder.

AVON & SOMERSET POLICE HQ, 2009

Detective Sergeant Julie Mackay, a 41-year-old single mother of three who has been overlooked for promotion for years, transfers to the Cold Case Unit. She unearths a file from the original inquiry and becomes hooked by the details: the rare blood type, Bath on a summer's night, the investigative wrong turns ... She takes on the case, and with the help of Melanie's inspirational mother works tirelessly to rebuild it.

This is the true story of how she did it.