When human remains are found on the central reservation of a motorway near London, Cassie and Sunny are called to the scene.

Dogged work leads the team to Hayley Reid, a 16-year-old girl who went missing on the eve of the millennium. The police's failure to find out what happened to Hayley wrecked her family's life. Cassie's compassion makes her determined to correct the mistakes made by the original investigating team - whatever the cost to herself.

A close-knit group of old school friends hold the key to what happened. Doctor Tim Finch, television presenter James Hollis, failing salesman Pete Carr and artist Chris Lowe. As the four suspects find themselves under the spotlight, their tight bond is put to the test. They all have secrets in their past - events that have pulled their lives apart. None of them are quite who they first seem to be, but is one of them capable of murder?