Francois discovers that Spitz is and praises Buck. As the dogs are about to be harnessed, Buck trots up to the spot that occupied, but Francois brings to the position of leader instead. Buck becomes very angry and will not let harness the team. Francois retaliates by bringing in a heavy . Remembering his lesson at the hands of the man in the red , Buck stays just out of reach. After an , Francois finally throws down the club, and makes a place for Buck in the of the team.
Francois is surprised and thrilled to learn that Buck excels at being the , whipping the rest of the team into shape. They make time back to and the whole team struts proudly through the town. After receiving their orders, and Francois leave the team in the care of a "Scotch half-breed," and leave Buck's life for good.
The work is now strict and heavy, as they are pulling the sleds back over the trail to . Life becomes the same every day, and Buck quickly achieves mastery over the other dogs. He loves to sit in front of the and dream about his memories from his previous life at Judge Miller’s home in .
They reach Dawson, and rather than the usual days of rest, they have another load of mail to deliver only days later. The way is much harder this time, for it has begun to snow. One dog named becomes terribly ill, but refuses to stop pulling the sled. The driver puts Sol-leks in his place to give Dave a break, but. Dave cannot stand to see another dog doing his . He runs in the soft beside Sol-leks, trying to resume his usual place. Finally the driver decides it is kinder to allow Dave to pull, for he will either way. During his final pull, he often and is caught in the traces of the sled. The next morning, Dave is too weak to rise. The team is driven ahead some ways, but they cannot ignore the that rings out. and everyone else know what the shot means.