Winning the bet allows John to pay off his debts and to journey east with his partners for a fabled lost mine. Buck leads a team of six dogs 70 miles up the Yukon. John Thornton is unafraid of the wild, so he hunts for their food each day, always certain that it will eventually appear. Buck is very happy as they trek through the wilderness, fishing, hunting and unthinking of time. For two years they wander, seeking an ancient cabin and a mythical mine. They never find the mind, but in the spring of teh second year they find a "shallow placer in a broad valley where the gold showed like yellow butter across the bottom of the washing-pan."
With little work to do, Buck spends his days by the fire, dreaming once more of that ancient man. In his mind he wanders in this early, undefined world. He remembers fear most of all, fear and constant vigilence. Along with this vision of the man, Buck nightly hears an ancient call deep in the forest. Sometimes he searches for it. Sometimes he hears it, springs from his place and runs wild through the forest. One night he hears it more clearly than ever before. He goes into the forest and he sees a timber wolf. Wishing to make friends, Buck approaches; but the wolf is afraid of this beast three times his size, and he flees. Several times this meeting is repeated, until finally the wolf understands Buck's intentions, and they sniff noses.
The wolf motions for Buck to come with him, and Buck is wildly happy as they run. He now understands what the call meant, running wild and free with his brothers. Suddenly, Buck remembers John Thornton. He turns back, and for an hour the wolf runs with him, confused, but finally Buck must go alone. When he enters camp he overwhelms John Thornton, so happy is he to see him. For two days he does not leave the camp or let John Thornton out of his sight. Then he once again becomes restless. Buck sleeps away from the camp, wandering the forest and searching for his wolf brother for days a time. He kills a black bear in a vicious fight, and when he returns to the kill and sees a pack of wolverines, he kills two of them as well. The urge to hunt and kill grows stronger in him.
Buck carries himself with greater pride, certain of his strength and viger. Only the splashes of brown and white on his muzzle and chest betray the fact that he is not a wolf. His instincts and reflexes are incredibly sharp. John and his partners say there has never been such a dog. When he leaves the camp, he transforms into a thing of the wild. He delights in killing his own food. In search of more difficult prey, Buck attacks a wild moose. It takes Buck a day to separate the bull from his herd. Then he follows him for another three, never letting him rest or get a drink of water. His kill finished, and refreshed by two meals, Buck heads back to camp and to John Thornton.
As he gets closer to camp, he suddenly begins to feel that something very bad has happened. back at the camp, Buck finds disaster. Everyone has been shot and killed with feathered arrows. The Yeehats are gleefully dancing Three miles out he sees a fresh trail, and he becomes more cautious. Suddenly he comes across the body of Nig, an arrow sticking from his head. He passes another dog almost dead, and then he passes the body of Hans. He sees Yeehat indians dancing around around the wreckage of the camp.
Buck leaps at the indians, ripping open the throat of the chief, and keeps killing until the rest of the tribe runs away in terror. For a few moments, Buck pursues them, killing a few more as they attempt to flee. Buck sees Pete's body, and then he follows the scent to the lake, where he knows John Thornton's body lies. Skeet, loyal to the end, lies dead just by the lake. Buck sits and contemplates the ache in his heart. He feels a bit better only when he looks at the bodies of the men he has killed. He realizes that men are no match for dogs without their arrows, clubs and spears.
That night Buck hears the call once more, and this time he knows he must leave for good. Nothing remains to hold him. The wolf pack rushes into the clearing, but they come to a halt upon seeing Buck. The boldest one strikes Buck and instantly has his neck broken. The rest descend, but Buck holds them off for half an hour. The wolves draw back, discomfited. One steps forward and whines softly. Buck recognizes his wild brother, and they touch noses. When the pack howls, Buck joins them. Obeying the law of club and fang, they accept his fellowship, and he runs with them into the woods.
After some years, the wolves of the valley are seen to have splashes of brown and white. Yeehats speak of a Ghost Dog that haunts the woods and slays the bravest hunter. One wolf returns to the valley each year. He sits and muses, remembering, howls once and then rejoins his pack.
At the beginning of this chapter, Buck's existence seems almost ideal. John Thornton and his partners embrace a natural lifestyle. Like the dogs themselves they prefer to hunt for their food. Rather than being depressed by hunger, the dogs enjoy the thrill of feasting some days and fasting on others. For Buck, it is almost like being with the ancient man he dreams of, for the dogs travel with the men, fighting for food, watching for danger, and constantly seeking the next destination. The needs of the men and the dogs are truly one.
This balance alters as soon as gold is found. John Thornton and his partners lose the wildness that joins them to their animals. In pursuing wealth, they have a goal that Buck cannot share, and they do work that he cannot share either. Buck's mind is taken over once again by the hairy, primitive man of the ancient world. Buck's desires become clearer along with his memories. he recalls that "the salient thing seemed fear." When Buck's ancestor wandered the forests with his human-companion, their needs and desires were always one. The human was as wild as the animal, seeking food, shelter, companionship, and safety. Buck craves and needs danger and insecurity in his life. Without it, he does not really feel alive.
When Buck takes to the forest, the reader might certainly wonder whether or not he will return to John Thornton. Buck is torn between his passionate love and his unquenchable desire to "heed the call." When he meets and runs with his wolf brother, he understands for the first time what that call means. Though Buck once again chooses John Thornton, it is clear that this situation cannot continue indefinitely. The ending of The Call of the Wild is difficult to understand. It is possible that London chose this ending, because only the death of John Thornton would free Buck from his divided loyalties. Furthermore, killing the Yeehat Indians truly connects Buck to his wild past. He now understands that his dependence on human companionship is false. Dogs do not need humans to survive, for dogs are stronger than humans.
Though Buck's allegiance to the wolf-pack is strong and true, London leaves the question of the relationship between man and dog unanswered. For all his wildness, Buck never lets go of his love for John Thornton. At the same time, it is clear that Buck should never have been tamed. Man has been altered by civilization, and while a dog may be kept from his true destiny, when the circumstances are right, his instinct for "wildness and wiliness" will always reappear.