London police detectives Cassie Stuart and Sunny Khan investigate historic cold cases involving missing persons, murder and long-hidden secrets.

Based on a true story, this four-part drama tells the story of the murder of 11-year-old Rhys Jones in Croxteth, Liverpool, in 2007. It explores Melanie’s and Steve’s ordeal, and tells of how Rhys’ murderer and associates were eventually brought to justice.

Three lifelong pals embark on a chaotic quest to solve the mystery of their old friend's suspicious death and keep their own dark secret under wraps.