On a hot August day in Paris, just over a century ago, a desperate guard burst into the office of the director of the Louvre and shouted, La Joconde, c'est partie! The Mona Lisa, she's gone! No one knew who was behind the heist. Was it an international gang of thieves? Was it an art-hungry American millionaire? Was it the young Spanish painter Pablo Picasso, who was about to remake the very art of painting? Travel back to an extraordinary period of revolutionary change: turn-of-the-century Paris. Walk its backstreets. Meet the infamous thieves - and detectives - of the era. And then slip back further in time and follow Leonardo da Vinci, painter of the Mona Lisa, through his dazzling, wondrously weird life. Discover the secret at the heart of the Mona Lisa—the most famous painting in the world should never have existed at all. Here is a middle-grade nonfiction, with black-and-white illustrations by Brett Helquist throughout, written at the pace of a thriller, shot through with stories of crime and celebrity, genius and beauty.