The national parks where Ranger Jo Lockwood works, on the edge of the New South Wales outback, are untamed stretches of dry forest cut through with wild rivers. She's often alone, and she likes it that way - until she discovers the body of a man, brutally murdered, in a vandalised campground.
Detective Senior Sergeant Nick Matheson knows organised crime and gang violence from the inside out. He's so good at undercover work that his colleagues aren't sure which side he's really on. His posting to Strathnairn is supposed to be a return to normal duties, but the murder victim in the campground is only the first of Jo's discoveries.
As Jo and Nick uncover drugs and a stash of illegal weapons, the evidence points towards locals - young men already on the wrong side of the law. But as far as Nick's concerned, it doesn't add up. When the body count starts mounting - each brutally punished before death - he becomes convinced that one person is behind the killings, one person is manipulating the men to commit horrific crimes, forming them into his own private drug-dealing cartel.
Jo has seen the man's face, and now she's his next target. Nick's determined to protect her, but trapped in the rugged outback he and Jo will have to act quickly if they are going to survive.