Red Ryder battles an unscrupulous fur thief named Hunter for the right to trap beaver and otter on the land of Chief Running Fox. Hunter attempts to ambush Ryder and his pal "Bear Trap" and when this fails, he kidnaps Little Beaver, grandson of the Chief, and kills the Judge, with whom the boy had been staying. But the boy manages to escape. The Duchess, Ryder's aunt, turns up and tries to persuade Ryder to return east with her. He discovers her and Little Beaver as stowaways in the supply train he is taking to the Indian camp. Hunter stages a fake Indian attack and attempts to recapture Little Beaver. The latter escapes and locates Running Fox who leads his warriors to the rescue. Hunter tries to escape by using Little Beaver as a shield, but he is knocked cold by the Duchess who sneaks up behind him. There is a joyful reunion between the old chief and his grandson, but Little Beaver elects to stay with Ryder and renounces his right to one day be chief in favor of Barking Squirrel.