You never forget your first case. Officer Walter O'Brien is called to a murder scene on his first night with Detroit PD.

A terrified young woman has bludgeoned her attacker with shocking skill. She is also a brilliant escape artist. Her flight from police custody makes the case impossible to solve - and, for Walter, impossible to forget. His fascination with the missing, grey-eyed woman approaches obsession.

And when Walter discovers that he's not alone in his search, only one thing is certain . . . The string of murders didn't begin in his home city - but he's going to make sure it ends there.