Brilliant. Complicated. Psycopath: that's the definition for the Four Monkey Killer or '4MK'; a murderer with a twisted vision and absolutely no mercy. Detective Sam Porter has hunted him for five long years, the recipient of box after box of grisly trinkets carved from the bodies of 4MK's victims. But now Porter has learnt the killer's twisted history and is racing to find 4MK's latest victim before it's too late.