A decade ago, psychologist Frieda Klein was sucked into the orbit of Dean Reeve, a psychopath who was obsessed with her. In the years since, Frieda has worked with --- and sometimes against --- the London police in solving their most baffling cases. But now she's in hiding, driven to isolation by Reeve. When a series of murders announces his return, Frieda must emerge from the shadows to confront her nemesis. Criminology student Lola Hayes has tracked Frieda down with a single-minded pursuit: she wants to delve inside the mind of a woman besieged by darkness. But in following every move Frieda makes, Lola is exposing herself to the same terrors --- and the same twisted fixation of a diabolical psychopath.