It's homecoming in Absaroka County, Wyoming, but the festivities are interrupted when a homeless boy wanders into town. A Mormon "lost boy," Cord Lynear is searching for his missing mother. Sheriff Longmire and companions Victoria Moretti and Henry Standing Bear embark on a high plains scavenger hunt to reunite mother and son. The trail leads to an interstate polygamy group that's harboring a stockpile of weapons and a vicious vendetta.

Wade Barsad, a man with a dubious past and a gift for making enemies, burned his wife Mary's horses in their barn; in retribution, she shot him in the head six times, or so the story goes. But Sheriff Walt Longmire doesn't believe Mary's confession and is determined to dig deeper. Unpinning his star to pose as an insurance investigator, Walt visits the Barsad ranch and discovers that everyone in town -- including a beautiful Guatemalan bartender and...