There’s some mythical gold mine in the North that has a lot of gold in it. Thornton uses the 1600 dollars Buck just won to set up an expedition in search of said mine.
Spring arrives and they still haven’t found what they’re looking for.
Buck and Thornton finally find what they’re looking for and that means gold.
Buck is still experiencing the Call of the wild.
Buck makes friends with a wolf.
Buck almost takes off for the wild, but remembers Thornton and returns to camp, where he is smothered with affection.
He kills a bear. We know what you’re thinking – holy cow, bears are huge. That’s the point; Buck is awesome. He is also reminded here of how much fun it is to kill things.
Buck starts to seem more like a wolf than a dog.
Fall comes and Buck kills a moose, which is no small feat.
Buck returns to camp to find that Thornton and his men have been killed by natives of the Yeehat tribe. He retaliates and the natives flee, calling Buck an "Evil Spirit."
Now that Thornton is gone, Buck is on his own again, and he can finally give in to this Call of the wild. He becomes the leader of the wolf pack and procreates.