Buck's original owner is Judge Miller, in Santa Clara California.
Buck is kidnapped by Manuel, and sold on the black market to people sending dogs to the Alaska Gold Rush.
Buck is bought by Perrault and Francois, defeats Spitz to become Perrault and Francois' lead dog.
Then Perrault and Francois have to sell their dogs, and Buck is bought by an abusive mail runner.
After one of the dogs in the team is Euthanized, Buck is sold to a family. The family is inexperienced and endangers the dogs and themselves. Buck is rescued from them by Joe Thornton.
Joe Thornton treats Buck lovingly, and Buck helps Thornton in return. They twice save each other's lives, and Buck helped Thornton win a bet that allowed him to find a Bonanza of a Gold Mine.
Buck then is lured away from the mining camp by the "Call of the Wild." He finds the source of the call to be a pack of Wolves. However, he is lured back to the camp by his loyalty to Thornton. Buck returns to find Thornton and his companions dead, and the camp looted by robbers.
Buck hunts down and decimates the robbers. He now has no owner, so he answers "The Call of the Wild," and joins the wolfpack as its Alpha Male.