Stolen by an evil workman from the warmth and happiness of his family's ranch in California, Buck is beaten into submission by his first owner, then re-sold to a French Canadian guide, Perrault, who takes him to Yukon, where only the fittest will survive.
Soon after arrival, he has to confront Spitz, Perrault's fierce and territorial lead dog, learning to kill rather than be killed, and takes his place at the head of Perrault's dog team, delivering mail packages to Dawson City.
There we meet John Thornton, his partner Pete, and Pete's young niece Helen, preparing to seek their fortune in Klondike gold. Maggie, the widowed proprietress of the Eldorado Saloon, and her young son Josh, complete the would-be family -- if Thornton's dream of gold turns into a reality. If not, Maggie must leave, alone, back to California.
When Perrault's partner is killed in a drunken bar-room brawl, he sells Buck and the rest of the dogs to the tenderfoot Charles Clark, who, with his spoiled wife Mercedes and her brother Hal, are searching for their own Klondike fortune.
Buck steadfastly leads Clark's bickering and ill-prepared party on their journey deeper and deeper into the heart of the Arctic darkness.
Buck (larger than most dogs) goes through many lives, trials, and tribulations finally realizing his potential. On the way he learns many concepts from surprise, to deceit, and cunning; he also learns loyalty, devotion, and love. As he is growing he feels the call of the wild.
You do not have to have read the book to follow the story. However being film much is accelerated and leaves less time for character and drama buildup. A few characters are removed but the main characters do not have to be modified to fill in the gaps.
For those that have read the book you will notice the narration is word for word extracted from the book. You may also recognize the narrator's voice as that of Richard Dreyfuss. The dialog was modified to cover much of the narration that was left out or the descriptions that were not portrayed.
A few stories were left out or modified for brevity. The main difference is a lot of the blood and guts were replaced with inferences and a story where he gets the stuffing beat out of him is replaced with a threat of being shot. My only disappointment was leaving out the part where Buck, as wild as he becomes, periodically visits the place of John Thornton's demise.