For over a century, the sands off Chatham, Cape Cod, held an explosive secret that could bring fame and fortune to those who knew it--until now. When friends Matt Gallagher, Tucker McKinney, and Annie Hopewell come to Chatham for one last summer together, they stumble upon an elusive clue to solving the mystery of a Confederate ship's lost cargo of gold. But just as they learn the value of their discovery, they become embroiled in a life-and-death struggle with professional felons, Carson Ridder and Buster Sykes--ruthless men who will stop at nothing to satisfy their greed. Hunted by Ridder and Sykes and wanted by the police, Matt, Tucker, and Annie embark on a race against time that takes them from the beaches of Chatham, to the secret passages of Harvard, and finally to the dunes of Monomoy Island--where they must solve the mystery or lose their lives.