It's a bad enough day for NYPD detective Callum Doyle when his cop partner is murdered. It's about to get a hell of a lot worse . . .

When the dead man's replacement is also brutally killed, suspicion falls on Doyle himself. Then he receives an anonymous message. This is just the beginning, it says. Anyone he gets close to will die - and that includes Doyle's own family. The only way to keep them alive is to stay away. For good.

Doyle is desperate to find out who is responsible, but when his every move puts others in danger he is forced to back off. With the investigation getting nowhere and his isolation deepening, Doyle has to ask himself an uncomfortable question: just how low is he prepared to sink in order to get his life back?