When Evelyn King and a family of Nansusequas Indians fail to return from a buffalo hunt, mountain man Nate King and his companion Shakespeare McNair set out to find them. Soon they begin to hear worrying tales of a band of white scalp hunters who have been killing and scalping every Indian they come across. But Evelyn and the Nansusequas turn up safe and sound after being rescued by freight owner Jeremiah Blunt. Nate is now in the man's debt—one that can be paid off easily if King would agree to protect the freight train, and deliver the goods to a colony of Shakers living in the Valley of Skulls. Sounds easy enough—except that a band of Pawnees are on the warpath on a personal vendetta. Nate King will need all his skills to keep everyone—including himself—alive