Recovering from his harrowing experiences in Mexico, Sheriff Walt Longmire returns to Absaroka County, Wyoming, to lick his wounds and try once again to maintain justice in a place with grudges that go back generations. When a shepherd is found dead, Longmire suspects it could be suicide. But the shepherd's connection to the Extepares, a powerful family of Basque ranchers with a history of violence, leads the sheriff into an intricate investigation of a possible murder.

As Walt searches for information about the shepherd, he comes across strange carvings on trees, as well as play money coupons from inside Mallo Cup candies, which he interprets as messages from his spiritual guide, Virgil White Buffalo. Longmire doesn't know how these little blue cards are appearing, but Virgil usually reaches out if a child is in danger. So when a young boy with ties to the Extepare clan arrives in town, the stakes grow even higher.

Even more complicating, a renegade wolf has been haunting the Bighorn Mountains, and the townspeople are out for blood. With both a wolf and a killer on the loose, Longmire follows a twisting trail of evidence, leading to dark and shocking conclusions.