It is a ferociously stormy night on the Island when fifteen year old Suzie, as she hurries to board her uncle's boat after a secret meeting with her boyfriend, is brutally stabbed to death. She is discovered by locals, held in the blood-smeared arms of Olly Matken, a schizophrenic teenager who grew up holidaying on the Island with Suzie's family. 'I didn't hurt her!' he says. 'All I did was protect her from the devil.'

When psychologist Karen Taylor sees DCI Charlie Trench's name flash up on her mobile phone, she knows that she ought to ignore the call, but curiosity and, although she won't admit it, a dangerous attraction to the brooding detective, send her headlong into a deeply troubling case.

Karen must decide; is Olly capable of murder? His psychologist doesn't think so, but the boy's own father seems to want to see his son charged. The only way to prove his innocence is to find out the identity of Olly's devil . . . so long as Karen can keep the demons from her own past at bay too.