John Paul Rocksavage is a hard-working cop in Liverpool city centre. When someone calls the police, it's Rocksavage who responds, coming face to face with human life in all its extremes. But when his partner, Andy, is murdered in a frenzied, vicious attack while on duty, Rocksavage suddenly finds himself bound to respond, in a way he never thought himself capable of. Events have suddenly become very personal, and once he's crossed the line from law enforcer to lawbreaker there's no going back. Meting out a unique brand of justice, while reconciling his own demons, his killings are not random, but organic and necessary.