Out of Range- C.J. Box

Game warden Joe Pickett is attempting to enjoy - all right, survive - his mother-in-law's wedding to a local big-shot rancher when he receives some disturbing news: Will Jensen, a fellow Wyoming game warden and a good friend, has killed himself. And Joe's been picked to temporarily run Jensen's Teton district. Jackson, Wyoming, is a far cry from Joe's hometown of Saddlestring - it's the epicenter for many environmental extremists and an elite playground for the rich and powerful, and Joe quickly finds himself in over his head. Yet despite the pressures of his new job, he can't get his friend's suicide out of his mind. By all accounts, Will had changed in the last few months, becoming violent and unpredictable.