Joe Pickett, recently fired from his job as a Wyoming game warden, is working on his father-in-law's ranch when he receives a visit from the governor. Governor Rulon - a devious but down-home politico - has a special request, one Joe knows he can't refuse. For weeks, the headlines have been abuzz with the story of Clay McCann, a lawyer who slaughtered four campers in a far-off corner of Yellowstone.

After the murders, McCann immediately turned himself in at the nearest ranger station. Seemed like a slam-dunk case for law enforcement - except that the crimes were committed in a thin sliver of land with zero residents and overlapping jurisdiction, the so-called free-fire zone. McCann has taken advantage of an obscure loophole in the law: neither the state nor the federal government can try him for his crime. The worst mass murderer in Wyoming history walks out of jail a free man.

Governor Rulon, sensitive to the rising tide of public outrage, wants his own investigation into the murders and will reinstate Joe as a game warden if he'll go to Yellowstone "without portfolio" to investigate. Joe, happy to get his badge back, even under these circumstances, agrees.

It quickly becomes clear to Joe that McCann is deeply involved with some illegal activity taking place in the park - something tremendously lucrative and unusually dangerous. As Joe and his partner Nate Romanowski search for the key to the murders, they discover that it may be hidden in the rugged terrain of the park itself.