Buck is a dog. Even though he has a personality and emotions, we need to still remember that he isn't human.
He also seems to be living the good life. He lives on a ranch in California, enjoys sunny weather, and is loved by his master.
So of course, something has to go wrong. In this case, the "something wrong" is that this guy Manuel, who works on the ranch, steals Buck and sells him off. Eventually, he ends up with this guy who wears a red sweater.
There may be something up with the red sweater. Keep an eye out for more red things.
Buck takes a beating from red sweater guy.
Then two French Canadian guys, Perrault and François, buy Buck.
There is much talk of Buck’s "worth." He’s like an alpha male, except a dog. An alpha dog.
So Buck ends up on a boat traveling north. We see how sheltered he has been because he gets a bit freaked out by snow. He’s from California, remember? Snow is a new thing for him.