Spitz and Buck fight each other to the death. Buck wins and takes a leadership position over the other sled dogs.
You got this Buck!
Buck is sold to Hal, Mercedes, and Charles. They are cruel, unexperienced owners and treat the dogs poorly.
Buck is malnourished and overworked, however, Hal continues to beat him. A bystander, John Thorton, speaks up and takes Buck from his abusive owners. Ultimately, this saves Buck's life.
Buck and Thorton develop a deep bond. Buck is willing to do anything for him. This bond led Thorton to betting that Buck could pull a thousand pounds for one thousand dollars. Buck succeeded and proved how close the two were.
John Thorton is killed by the Yeehat tribe. Buck is devastated and seeks revenge on the tribe by slaughtering all members of the tribe he could track down.
With no ties left to humans, Buck joins a wolf pack in the forest. He answered the call of the wild.