Buck is a dog living a charmed life on the estate of Judge Miller, during the time of the Klondike Gold Rush in 1897. He is the king of all the animals on the estate and as such enjoys special privileges, such as the run of the estate and the admirable position of being the Judge's favorite dog. However, he is stolen by the gardener's assistant, Manuel, and sold to finance his gambling addiction. He is shipped to Seattle. Put in a crate, he is starved and ill-treated. When released, he attacks his overseer, known only as the Man in the Red Sweater but is badly beaten and taught to respect the "law of the club". Buck is then sold to a pair of French-Canadian mailers named François and Perrault, who take him to the Klondike region of Alaska, where he meets other sled dogs. He is eventually sold to a kind man named John Thornton and begins to become a part of the wild. After Thornton's death, Buck becomes independent and leader of the wolf pack.
- He was a gardener in the book, but in the 1972 film, he was a housekeeper.
- In the 1972 film, Judge Miller had another assistant named Jack.
- In the 1976 film, Manuel claimed that he would be fired by Judge Miller for stealing Buck.
- In the 1997 film Call of the Wild: Dog of the Yukon, Manuel is credited as "The Kidnapper" and his face was not shown.
- It is currently unknown if he will appear in the 2019 film directed by Chris Sanders, though he will be replaced by an unnamed butler played by Hal Dion.
- In Disney's White Fang, Buck made two cameo appearances where he is sold to Alaska and bought by Beauty Smith to become a fighting dog.