This book tells the exciting story of how a cryptographer helped capture rum runners and break up Nazi spy rings. The back matter shows kids how they can crack the code and exchange secret messages with their friends. Scattered throughout the book's illustrations are hidden messages for kids to find and decode. For those who want to learn more, the back matter also includes a description of how codes and ciphers work, as well as information about cryptography today. Readers will learn how to keep their information safe, whether shopping online, surfing the web, or simply texting.