Buck, a big, powerful dog, is kidnapped from his California home and sold as a sled dog in the Arctic.

In his new environment, he must learn quickly how to deal with man's club and dog's fang, or he will not be able to survive.

Buck not only survives, but becomes a leader of dogs, and eventually a a leader of wolves.

He is transformed by two almost opposite forces. His love for John Thornton who saved his life, and the memories that awaken within him of the ways of his ancestors, both dogs and wolves.