Stolen from a comfortable estate in the Santa Clara Valley during the gold rush of eighteen ninety-seven, a powerful St. Bernard and Scotch collie mix named Buck is shipped into the frozen chaos of the Klondike. Thrust into the demanding life of a sled dog, he faces immediate violence, enduring the harsh discipline of the club and the ruthless survival of the pack. Through relentless toil and starvation, Buck sheds his civilized morality, allowing ancient instincts inherited from his wild ancestors to awaken within him. He learns to steal for survival, fights for dominance against the lead dog Spitz, and ultimately kills his rival to claim the leadership of the government mail team.
After enduring immense physical exhaustion on the grueling trails between Dawson and Skaguay, Buck is rescued from incompetent and cruel new owners by a frontier outdoorsman named John Thornton. For the first time, Buck experiences genuine, passionate love and devotion toward a master who saves his life. He repays this loyalty through legendary feats of strength, including winning a massive thousand-dollar wager by starting and hauling a loaded sled weighing half a ton, and repeatedly saving Thornton from drowning in raging river rapids. Even amidst this deep human bond, the call of the wild echoes persistently through the surrounding forests, drawing Buck toward his ancestral home.
The narrative reaches a tragic turning point when a band of Yeehat Indians slaughters Thornton and his companions. Unbound at last by human ties, Buck unleashes his fury upon the murderers, destroying their camp before finally answering the permanent call of the wild. He joins a pack of timber wolves, becoming a legendary ghost dog whose bloodline and presence haunt the northern valleys for generations to come.