in the Midwest to take lessons, while her friends Bess and George perfect their horseback riding. But soon the young sleuth is confronted with the mystery of a hijacked plane and a missing pilot. Then the rancher's prize pony, Major, is stolen. Nancy becomes a detective in a plane and on horseback to track down the elusive sky phantom and the horse thief. A lucky find - a medal with a message to be deciphered on it - furnishes a worthwhile clue. Romance is added to mystery when Bess becomes interested in a handsome cowboy. Readers will spur Nancy on as she investigates a strange magnetic cloud, hunts for the horse thief, and finally arrives at a surprising solution.