 O Rourke and his Cree half brother Cajou are returning from a northern Canadian trapping trip when they encoutner a burned wagon train and sole surivor Grace. Naive Mountie commander Benton believes it to be a Cree attack. The Sioux from across the border are trying to force the Cree into being allies in their struggle with the U.S. seventh cavalry. O Rourke must mutiny to save the men. He must also aid Grace, in whom Marshal Smith has both official and unprovoked amorous interests.