Bitterroot - James Lee Burke

When Billy Bob Holland visits his old friend Doc Voss, he finds himself caught up in a horrific tragedy. Doc's daughter has been brutally attacked by bikers, and the ring leader, Lamar Ellison, walks free when the DNA samples "get lost". Then Ellison is burned alive and Doc is arrested. So much for Billy Bob's vacation...

Doc needs a lawyer, and fast. And that's not all. Newly released killer Wyatt Dixon has tracked Billy Bob to Montana, bent on avenging the death of his sister for which he holds Billy Bob responsible. And Wyatt is only one thread of a tangled web of evil that includes neo-Nazi militias, gold miners who tip cyanide into the rivers, a paedophile ring, and the Mob. As the corpses of the guilty and innocent pile up, Billy Bob stands alone.