Buck is a large powerfull domesticated dog half st bernardan half sheepdog who lives a comfortable life in the home of judge miller in santa clara california. He is kidnapped by a gardener and sold to traders so theycan meet the growing demand for strong sled dogs in the klondike region of canada following the discovery of gold in the area. Dogs like buck are needed topull the sleds through the deep snow fields. The trader's are brutal men who use clubs to beat buck to teach him to obey them. Buck fights against his cruel masterand attempts to escape without success. Buck soon learns that a man with a clubis a master who must be obeyed.