When skeletal remains are found beneath the fortified walls of an ancient castle on Northumberland's rugged coastline, DCI Kate Daniels calls on a forensic anthropologist to help identify the corpse.
Meanwhile, newly widowed prison psychologist Emily McCann finds herself drawn into the fantasy of convicted sex offender, Walter Fearon. As his mind games become more and more intense, is it possible that Daniels' case has something to do with his murderous past? With his release imminent, what exactly does he have in mind for Emily?
As Daniels encounters dead end after dead end and the body count rises, it soon becomes apparent that someone is hiding more than one deadly secret . . .