When Debbie Danforth discovers a flaw in the genealogy of her live-in boyfriend, Jeremy Hadley, he and his family try to discredit her findings, but eventually admit they must be true. Jeremy and Debbie run a private detective business, the Sandley Agency and commit their skills and resources to learning about the impostor Debbie has discovered in the Hadley ancestry. They are assisted in this effort by Penny and Joe Gonzalez, principals in a covert federal agency, with whom Jeremy has previously worked as a consultant. Their joint investigation uncovers both unique details concerning the mysterious Hadley impostor and little-known facts about events leading up to World War II in both Britain and the United States. Was the person who masqueraded as a Hadley a villain or a hero? Did other Hadleys know he was a fraudulent member of their family? Did his actions assist or impede the British and the Americans as they faced the growing menace in Europe?