With Buck at the head of the team, Francois and Perrault’s sled makes record time. However, the men soon turn the team over to a mail carrier who forces the dogs to carry much heavier loads. In the midst of a particularly arduous trip, one of the dogs becomes ill, and eventually the driver has to shoot him. At the end of this journey, the dogs are exhausted, and the mail carrier sells them to a group of American gold hunters—Hal, Charles, and Mercedes.