Winning the allows John to pay off his debts and to journey east with his partners to look for a famous lost mine. Buck and other dogs travel 70 miles up the Yukon. Buck is very happy as they travel through the wilderness, fishing, and . For two they wander, looking for an ancient cabin and a mythical mine. Eventually they get to a place where they find thousands of dollars in gold.
With little work to do, Buck spends his days by the fire dreaming once more of that ancient man. Buck hears nightly the ancient call of the from deep in the forest. One night he goes into the forest and he sees a timber wolf. Buck is much larger in size than the . Buck wants to become with the wolf, and they eventually sniff , which shows that they were friendly towards each other.
Buck is wildly happy as he is running wild and free with his brothers. Suddenly, Buck remembers John , which causes Buck to turn back and return to John Thornton’s camp. For days he does not leave the camp or let Thornton out of his sight. Then he once again becomes restless, and begins wandering the and searching for his wolf friend. He kills a black in a vicious fight, and when he returns to the kill and sees a pack of , he kills two of them as well. The urge to hunt and kill grows stronger in him.
Buck’s and reflexes are incredibly sharp. When he leaves the camp, he transforms into a thing of the wild. He really enjoys killing his own food. In search of more difficult prey, Buck attacks a wild . After killing the moose, Buck heads back to camp and to John Thornton.
As he gets closer to camp, he suddenly begins to feel that something very has happened. Back at the camp, Buck finds that everyone has been shot dead with feathered . He sees Yeehat Indians dancing around the wreckage of the camp.
Buck leaps at the , ripping open the throat of the chief, and keeps killing until the rest of the runs away in terror. Buck is very upset, but 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, and spears.
That night Buck hears the call once more, and this time he knows he must for good. A wolf pack rushes into the clearing, but they come to a quick stop once they see Buck. The boldest one attacks Buck and instantly has his broken. The rest attack, but Buck holds them off for half an hour. One steps forward and whines softly. Buck recognizes his wild brother, and they touch noses. When the pack , Buck joins them. Obeying the law of club and , they accept his fellowship, and he runs with them into the woods.
After some years, the wolves of the valley are seen to have with splashes of brown and white. The speak of a Ghost Dog that the woods and kill the bravest hunter. One wolf returns to the valley each year. He sits and thinks, remembering, then howls once and rejoins his pack.