Based on the Marguerite Henry novel "Misty of Chincoteague." Every year some of the wild ponies who live on the islands off the Virginia coast are rounded up and auctioned off to thin out the herd. Young Paul and Maureen Beebe want to help capture the elusive Phantom so they can buy her, but they discover the mare has had a foal and they name her Misty. Only when the duo comes up for sale, they are bought by someone else.