C J Box has another winner with this story and the Wolf Pack of the title cleverly references both wolves of the human and animal varieties.
In this story a rather nasty fellow is in witness protection and he comes to the attention of ranger Joe Pickett when he callously causes multiple wildlife deaths. The protected witness thinks nothing can touch him because he is valuable to the government and the wildlife service are warned off trying to bring the man to justice because of this value but Joe is a stickler for what is right and he just can't let sleeping wolves lie. A lot happens before the end but I won't put in any spoilers. Suffice it to say, it's a great read and the story tears along at a cracking pace.
My only mild annoyance with the story is that usually there is an epilogue at the end where we all sit down and contemplate the gravity of the events that have happened and get a bit of closure but in this story the epilogue appears and then there's an action flashback which is just annoying and unsettling. I wish Mr Box had put the action flashback where it belonged at the end of the action and not interrupted the winding down and reflection process of the epilogue. It jolted this reader unpleasantly.