Dorothy Boone's attempt to help a friend leads her to an encounter with a deadly new rival. Trafalgar and Boone have been working together for a year, taking small commissions in order to learn how to work together. When a friend and colleague is committed to an asylum following a disastrous mission in the Mediterranean, Dorothy takes it upon herself to uncover the truth. What she finds is that her friend was close to the discovery of a lifetime: the remnants of a prehistoric civilization who might have been wiped out by the Biblical Flood. Trafalgar agrees to accompany her on an expedition to finish what her friend began, and soon they run afoul of a powerful enemy: Emmeline Potter, called Virago, is a treasure hunter who is also adept at magic and seeks riches to help fund a violent uprising. Dorothy and Trafalgar must race to defeat their unscrupulous opponent if they hope to preserve the site for future generations, but they soon discover Virago may be the least of their worries. The secrets of the past have ways of remaining hidden, and trying to uncover them may cost Dorothy her life.