The Kindness of Dragons - Akitada mysteries, #18

On a visit to a remote mountain region with his children, Akitada hopes to find some peace after the break-up of his marriage. Instead they become involved almost immediately in the random violence that plagues the peasants of the valley. Farmers are murdered, rice stores are burned, and young girls disappear. The local policeman seems honest, but soon Akitada fears to trust anyone. When his retainer is arrested for murder and his daughter nearly caught by bandits, he fights back.
Powerless and far from court, he must confront the ruthless villain behind the crimes.