Buck, a powerful dog, half St. Bernard and half sheepdog, lives on Judge Miller’s property in California’s Santa Clara Valley. He leads a comfortable life there, but it comes to an end when men discover gold in the Klondike region of Canada and a great demand rises for strong dogs to pull sleds. Buck is kidnapped by a gardener on the Miller property and sold to dog traders, who teach Buck to obey them by beating him with a club and,ship him north to the Klondike.