Recovering buried treasure by tracing a strange assortment of clues is a challenging exercise for Joan Burton, editor of the Globe, a school paper, and popular student at Guilford in the heart of New York City. A natural born sleuth, Joan decodes a message found in a book of baseball stories featuring a diagram of the Guilford baseball diamond. With the help of Peter, a new boy in town, Joan compiles a list of suspects, uncovers the truth about a scandal and robbery that took place many years ago and learns a great deal about New York City. Her unknown rival for the treasure turns out to be a boy who is connected with the past events by family descent. A lively mystery loses impact because its various parts are separated by reams of extraneous matter. Joan's school and social life, sketched in heavily against a New York background, hamper continuity and reduce suspense to a minimum.