In the rugged frontier of the 1887 Ozark hills, the scars from the Civil War are raw. Organized law has failed to protect its citizens. Lawlessness and chaos rein. Responding to murders gone unpunished and savagery of every sort, Dave Walker, a farmer and church deacon, leads a righteous vigilante group known as the Bald Knobbers on armed night rides to protect their families and way of life. In response, a sheriff of questionable scruples is appointed by the governor to end their activities and return order. Dave and his wife Sarah have two sons. Will is seventeen years old, full of fire and vinegar and recently voted second in charge of the Bald Knobber organization. Rube is eleven years old and a strange child. Vastly intelligent, Rube is beset with visions, bizarre behavior and spends his days speaking with animals. The troubled child has a tempest building within himself. Dave Walker's riders share the rugged timber with older and darker things. The mysterious Indian shaman Abraham White Tree seems made of shadow and fog. Shunned and hunted by his tribe and the white men alike, he practices the old ways and feels that Walker's son Rube is special; perhaps even the return of the ancient being from legend, The Thunder Helper. White Tree befriends the boy to help guide his spirit. The law, the government, honor and the code of the hills are set on a collision course. Their lives soon become a red-hot kettle, boiling over with violence and bloodshed before the nation's eyes. As the lines of justice and honor blur, can Dave Walker and his family, or even their society itself survive When The Thunder Comes?