"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...