Robert MacTavish is appointed the head commissioner of the Hudson Bay Company in the Canadian Northwest over Angus Fitzpatrick, the company's trade agent. Fitzpatrick then accuses MacTavish's son Donald, who loves Fitzpatrick's daughter Jeanne, of being the leader of the Free Traders, who have stolen many of the company's furs. To clear his name, Donald vows to capture the gang. The real leader, a half-breed named Sergius, kidnaps Jeanne by convincing his Indian mother, Old Mary, to lure her to his cabin to marry him, because then Fitzpatrick would never arrest him. Fitzpatrick is told that Donald has abducted Jeanne, and he threatens to hang him. After Donald is captured, he escapes and rescues Jeanne. They then find Angus, who was injured fighting the Free Traders. Donald stops an employee revolt, and leads them in battle against the Free Traders. During the fight, Sergius starts to escape, but his mother stops him. After Sergius shoots her, Donald kills him in a knife duel.