Archaeologist Conrad Yeats discovers in his father¿s tombstone the key to a centuries-old warning built into the very design of Washington, D.C. Major monuments along the National Mall are astronomically aligned and are about to lock with the stars at a date unforeseen by the Founding Fathers. Along with Serena Serghetti, a beautiful Vatican linguist with secrets of her own, Yeats explores the hidden world beneath the capital in a deadly race to save it.