The story begins in the fall of 1897, at the time of the Klondike Gold Rush. Buck is a large, one-hundred and forty pound dog who lives on a ranch owned by Judge Miller in Santa Clara, California, some forty miles south of San Francisco.
Buck is four years old and has an enjoyable life. Unlike the other, smaller dogs on the ranch, he is allowed to roam over the entire property. He goes into the swimming tank, hunts with the judge's sons, and escorts the judge's daughters on their morning walks. In the winter he lies at the feet of the judge in front of the fire in the library. He is like a king who lords it over all the other creatures, and is treated with respect by everyone.
Buck's comfortable life is ended when Manuel, one of the gardener's helpers, take him for a walk and sells him to a man who treats him roughly and throws him into the baggage car of a train. Halfway through the night Buck is transferred to a cage-like crate. In the morning, four men come to pick up the crate. They amuse themselves by poking sticks at him. Buck is conveyed to a railway depot, where he is placed in an express car. He stays there for two days and nights, during which he neither eats nor drinks. He is bundled off the train at Seattle, where a man in a red sweater takes charge of him. The man lets Buck out of the cage, and Buck attacks him in fury, but the man brutally beats him into submission with a club. Buck is beaten but his spirit is not broken. In the days that follow, more dogs arrive, and Buck watches as they are beaten in the same fashion. Adapting to his new situation, Buck realizes that the man is the master and must be obeyed.
Buck is then sold to a man named Perrault, a Canadian government mail-driver, who realizes from Buck's impressive appearance that he is a dog in a thousand. Along with a dog named Curly, they travel north on the deck of the ship, Narwhal. The dogs are turned over to Fran´┐Żois, a swarthy French-Canadian. Buck learns to respect both men, since they are calm and fair. There are two other dogs on the ship, a big dog from Spitzbergen, and a gloomy one named Dave, who just likes to be left alone. The weather gets colder as they head north, and Buck encounters snow for the first time.
The Call of the Wild can be read simply as an adventure story about a dog, but most commentators see in it something deeper than that. There are many parallels between the world of dogs and the world of humans, so the novel can be read as a kind of human allegory. Buck himself is given emotions such as pride and shame, and an awareness of abstract ideas such as justice.
In the first chapter Buck takes the first steps to discovering a different kind of law of life than he has known at Judge Miller's ranch. His life there is very orderly and civilized. He is like a "sated aristocrat"; he is compared to a country gentleman and a lord (since he is lord over all the other animals on the ranch). In this civilized life, wild impulses are tamed. Buck enjoys comfort and privilege. He does not have to fight for anything; all his needs are provided for. He has not had to earn his position; like an aristocrat, he was born to it. But his deeper nature is unknown to him, and this is what he will discover during the course of the novel. It is a painful journey. In chapter 1, for example, he learns for the first time that there can be other relationships between man and dog than the one he has known. The man in the red sweater who clubs him into submission is his introduction to a ruthless world in which the strong rule, and Buck makes his first adaptation to it.