Buck is now to be raised as a sled dog and put through brutal conditions. Francois and Perrault who are now the owners have them go through harsh conditions in the Klondike to get to where the gold is.
Buck takes on a battle with Spitz and then wins so he is now head of the group. He travels until his owners then sell him. This then takes him to his new owner where they don't know what there doing. At all having most of the dogs die or almost killing them. Almost killing Buck John Thornton takes Buck from the owners. Buck learns to feel love towards John and would protect him no matter what. Later on in the story John is out in the woods where they then struck gold. Buck gets bored and starts reconnecting with the wild but still comes back home to John.
In this part John Thornton is attacked by Indians called the Yeehats. Everybody at the camp where Buck was at was killed in the battle. Buck then went into a fury killing most of the Indians. This causing them to panic and seize. From that day on they became scared of Buck knowing he was like nothing else.
After losing John Thornton, Buck roamed around in woods until the wolf pack had at last crossed over to his lands. He was challenged and won the battle meeting his wolf-brother that he had known earlier on. Buck from then on was part of the wold back running side by side with his wild brother.
At the end it's about how the Yeehat tribe became scared of the ghost dog that was in the wolfs pack. In the winters they can see him passing in the moonlight at the front of the pack. Described as wolf-like but, yet not. His great throat a-bellow as he sings a song of the younger world, which is the song of the pack. This is where Buck is finally in the call of the wild.