The trading post of Sitkawan, Canada is taken by surprise when an Indian tribe attacks and massacres the settlers aboard a fur-bearing wagon train. Sergeant MacLane of the Royal Canadian Mounted Police is assigned to investigate the case. MacLane soon realises that the attackers were led by Mort Ransome, a nasty renegade, who had been conspiring with Black Bear, medicine man of the tribe, to incite the heretofore friendly Indians for his own gain. He also learns that two white renegades have kidnapped Diana Blake, daughter of the local post factor, and saves her from a runaway wagon just before it plunges over a cliff. ''Perils of the Royal Mounted'' also features stereotypically Northern (genre) elements including fur trappers, lumberjacks, trading posts, rebellious Indian braves, forest fires, avalanches, and a wide range of dangerous wildlife.