Nancy receives a letter meant for a British heiress who has the same name and, in her attempts to contact the other young woman, faces danger from a man who operates a Lonely Hearts Club mail fraud.

Nancy arrives in Phoenix, Arizona, eagerly looking forward to a fun-filled vacation at Shadow Ranch but finds herself embroiled in a baffling mystery involving a phantom horse and buried treasure. Local people believe that the ghostly animal is carrying out the curse of Dirk Valentine, the romantic outlaw who was killed many years ago at Shadow Ranch, where he had gone to fulfill a promise to his sweetheart. Suspecting that a treasure hidden by Valentine...

Nancy Drew investigates when a pony from the petting zoo keeps escaping from his pen.