Jules Lagarre, a half-breed brigand, undertakes to dominate the Canadian Northwest with the aid of Indians and cutthroats. André Audemard, a trading post merchant, appeals to the government for help and is murdered by Lagarre's henchmen, Lupin and François, leaving his children, Jeanne-Marie and Roger. Lagarre attempts to establish himself as head of a provisional republic, but the Canadian government forms the Northwest Mounted Police to establish law and order. Jeanne-Marie persuades the settlers to remain, and she falls in love with Sergeant Carrigan. Roger murders Lupin and François in a rage, for the killing of his parents, and Carrigan comes to arrest him; as a result, Jeanne-Marie turns against him. Lagarre organizes an Indian attack on the post and orders the forest set afire to hem off the Mounted Police; however, the rescue is effected. Roger dies protecting Jeanne, and she is reconciled with Carrigan.