 After four fur trappers have been slain and their furs stolen, Corporal Rod Webb (Kirby Grant) of the Royal Northwest Mounted Police sets out for their village. En route he and his dog Chinook come upon another trapper, Henri (Edward Norris), shot and lying unconscious on the trail, and the furs he was delivering to the factor, McTavish (Charles Lang), stolen. Chinook trails the would-be-killer Muskoka (Ted Hecht) and bites a piece of cloth from his coat before he escapes. Webb leaves Henri with Greta (Jan Clayton) while he investigates, aided by Minnetaki (Elizabeth Root), Indian servant fired by McTavish, the real head of the fur thieves, and Marcia Cameron (Helen Parrish), wife of the superintendent (Luther Crockett) of the trading company that employs McTavish.