In the late 1800s during the Klondike Gold Rush, a powerful and pampered St. Bernard-Scotch Collie dog named Buck lives a comfortable life in California. His world is turned upside down when he is stolen from his home and sold into the brutal life of an Alaskan sled dog. Buck is transported to the Yukon, where he is initially mistreated but is eventually rescued by John Thornton, a kind-hearted prospector. As Buck adapts to his new life, he discovers his primal instincts and becomes the leader of a dog sled team, delivering mail across the harsh Northern landscapes.

The once-domesticated Buck now faces the unforgiving wilderness, forming a close bond with Thornton. Together, they embark on an adventure, with Buck learning to survive in the wild and earning the respect of the local sled dogs and their handlers. As Thornton and Buck deepen their connection, they encounter both the breathtaking beauty and the perilous dangers of the untamed land. Buck's journey of self-discovery brings out his true spirit and calls him towards a life that is far from the comforts of his origins.