A wilderness girl raises a deer and a mountain lion to be friends.

Toni Martin and her father Matthew live in the High Sierras with their cook Sang Soo and his infant son Feng. One day, while hiking through the wilderness, Toni discovers a young unprotected puma cub, whose mother has been caught in a man-made trap, being pursued by a wolf, and decides to help bring it to safety. Later, Toni adopts a young fawn that is being chased by a pack of dogs belonging to the nefarious Bergman, a local rancher and hunting party leader, and the dogs chase Toni and her newfound friends until ranger Bob Alden saves them. Grateful for his help, Toni invites Bob to meet her father, a struggling writer, and the three discuss the predatory practices of animals, debating Toni and Matthew's hypothesis that two animals such as a baby puma and a fawn, instinctive enemies, can be raised to live in harmony. Bob disagrees with the Martins and mentions that though it is his job to capture pumas for the state, which pays him twenty dollars a piece for their hides, he is willing to overlook this case while Toni and her father conduct an experiment to test their hypothesis. Matthew finds a subject for a new book in Toni's experiment, but Bob is certain that the two animals will eventually revert to type and disappoint them. Toni names the puma Gato and the fawn Malibu and watches them grow up as friends. One day, when Gato is blamed for raiding Bergman's nearby chicken coop, Bob is forced to insist that Toni set her animals free. Reluctantly, Toni turns Gato and Malibu loose to brave forest fires, storms and other natural hardships on their own. A few years later, Toni and her father, whose book has been a great success, are visited by Gato and Malibu, who lead Toni to a giant animal trap built by Bergman and his men. Malibu gets caught in the trap, but with the help of Toni and Gato, he is freed. One afternoon, while tending to the young Feng Soo, Toni leaves the child tethered to Malibu's son while she takes a swim, and just as a rattlesnake threatens to attack the unafraid boy, Malibu happens upon the scene and quickly stomps the snake to death. When Bergman and his men attempt to rustle a number of deer out from the National Park to be used as kill for a hunting party, Malibu saves them by showing them how to jump over the corral fence. Bergman goes after Malibu, but when Gato comes to the deer's aid, Bergman wrestles with the puma until he forces Gato over the edge of a cliff. Gato lands safely, but Malibu charges Bergman and bucks him over the precipice to his death. A romance between Toni and Bob flourishes, and Bob, convinced of the success of Toni's experiment, presents her with a gift that is sure to please her: a notice proclaiming the extension of the government game refuge boundary lines, which will secure the protection of Gato, Malibu and other animals from hunters.