The dark horse
(Book)

Series from jacket.

Wade Barsad, a man with a dubious past, locked his wife Mary's horses in their barn and then burned it down. In return she shot him in the head six times - or so the story goes. Sheriff Walt Longmire doesn't believe that Mary's confession is the truth, and he's determined to dig deeper. Posing as an insurance claim investigator, Walt goes undercover and soon discovers that the population of an entire town might have wanted Wade dead.