Even in the wilderness, trouble seems to find Karl Bergman. Years after his run-in with a serial killer on the Appalachian Trail, Bergman sets out with his dog, Blazer, on a thru-hike of the Pacific Crest Trail—hoping to return home a better man. But the discovery of a dead body on the outskirts of the Anza-Borrego Desert threatens to embroil Bergman in another violent chain of events with even higher stakes than his previous ordeal. This time his adversary is not just one man as the dead body appears to be linked to a drug cartel using mules to move product from Mexico to Canada. An uneasy alliance with a San Diego narcotics officer makes things more difficult, but when Bergman reconnects with his estranged son Kenny, a sophomore at UCLA, he puts both of them in grave danger that can only be escaped by bringing down the cartel's operation.