Buck, the dog, lives in Santa Clara, California Valley with Judge Miller. He is the best possession by the judge. Within the same period, the discovery of gold is made in the North. Big dogs become valuable as they can be used to carry heavy sleds. Buck is sold by the judge’s servant and later to the northern dog traders. Because of the decent life, Buck is used to, and he finds it hard to adjust to the way the other dogs live. However, he has to adjust to being tied and controlled by the new masters. He also has to learn to deal with the attacks from the other dogs. Because of hunger, he has to learn how to kill and feed in raw meat.
After fights with Splitz and winning, Buck is now the leader of the other dogs. Because of the superiority over the other dogs, Buck becomes the favorite of François and Perrault, their masters. The masters, however, have to attend to other duties and are replaced a Scott. The new master overworks Bucks to a level he cannot endure. Some dogs die because of harsh conditions. Buck survives the ordeal though he has lost much weighing. He is later sold to Mercedes, Charles, and Hal. Due to their incompetence, Buck cannot even get enough food. John Thornton rescues him.
John Thornton treats Buck well until he recovers. Though Buck lives well under John Thornton’s care, he still feels he should go back to the wild. In one instance, Buck saves Thornton from drowning. Later, Buck moves a heavy sled to help Thornton win a bet. With the money that he wins, Thornton searches for the gold mine lost previously. Mining of the gold takes much time.
As the other men are planning, Buck goes to the wilderness to look for wolves and other wild animals. There is a time he wanders for four days and returns to find John Thornton and his men murdered in the hands of Yeehat Indians. He attacks and kills some of the Indians while others escape. Since the master is dead Buck is now free and becomes part of the wild wolves. That marks the end of the book written by Jack London.