Skelettet af en ung kvinde bliver fundet i midterrabatten af en motorvej. Hvem var kvinden, og hvordan kom hun af dage? Politifolkene Cassie Stuart og Sunny Khan går på jagt efter svarene. Samtidig, rundt omkring i England, går livet videre for fire gamle skolekammerater. Ingen af dem aner, at de snart kommer i politiets søgelys.

Cassie and Sunny go in search of Hayley's family as the press begin to take an interest in the story. A detective who was involved in the original investigation offers his thoughts on why her disappearance remained unsolved, pointing out that Hayley's boyfriend was suspected of the crime but was never charged. The distance between where Hayley was last seen and where her body was found leads Cassie to form a new theory - that the killer may have travelled up from London, then returned before they could be questioned.

It becomes clear to the detectives that the four men have conspired to come up with a false account of what took place the night Hayley disappeared. Jake is assigned to track down Tim Finch's ex-wife to hear her version of events - and uncovers disturbing information about Chris Lowe's past. On a personal front, Sunny is offered the opportunity to rekindle his past marriage, and Cassie worries about her father's failing memory.

Hvem dræbte Hayley Reid? Under stor mediebevågenhed kæmper Cassie Stuart og Sunny Khan for at få sandheden om det 18 år gamle mord frem i lyset.

Following the discovery of seemingly incriminating items found at his house, Tim insists he bought them for his girls at a fete in Middenham. However, the team are not buying Tim's story. A new discovery leaves the team shocked and devastated, hitting Cassie particularly hard.