Sergeant Tom Flynn of the Royal Canadian Mounted Police suspects that a youth was killed by Mach de Fer, a vicious wolf dog. Père Brissaud maintains an iron grip on the fur trade in the fabled Valley of the Thousand Smokes. What has Marie Brissaud to do with this man? Flynn finds the answers in a desperate chase through a blizzard, and the inevitable clash between his lead dog, and the deadly Mach de Fer!