After four fur trappers are slain and their furs stolen, Corporal Rod Webb of the Royal Northwest Mounted Police sets out for their village. En route, he and his German Shepherd, Chinook, encounter another trapper, Henri, unconscious on the trail, and the furs he was delivering to the factor, McTavish, stolen. Chinook trails the would-be-killer and bites a piece of cloth from his coat before he escapes. Webb leaves Henri with Greta while he investigates, aided by an Indian servant and the, wife of the superintendent of the trading company that employs McTavish.