The remarkable true story behind one of history's most enigmatic portraits--"a glorious picaresque of unbridled passions and unmitigated scoundrels, a glorious romp through the great palaces and palazzos of Europe" (Amanda Foreman, New York Times best-selling author of Georgiana, Duchess of Devonshire) Five hundred and thirty years ago, a young woman sat before a Grecian-nosed artist known as Leonardo da Vinci. Her name...