This story of a little burro is a tale of southwestern deserts and mountains, of domestication and wildness. For Dusty had been born in captivity, knew only kindness, and, when sold to a hard-driving, cruel cattle rustler, took her chance at escape when the time came. Her escape took her among the bighorns, and to the shack of prospector Andrews who was able to tame her back into harness. But her encounter with Big Jack, of the wild burro pack, results in a foal of her own, Mousey, and when Andrews doesn't appear she joins Big Jack's herd in all their dangers of existence. On their return from the mountains she finds Andrews again -- and chooses human companionship for keeps.