Florence, 1502. Marshal Louis de La Trémouille's small army has stopped off en route to Naples to buy objects d'art for King Louis XII of France. Naturally, Leonardo da Vinci's workshop is on the shopping list; and during their visit to his house, the young nobleman de Bougainville chances upon the not-quite-finished Mona Lisa. He promptly, utterly and hopelessly falls in love with the woman in the painting, and is determined to find her - despite rumours that she has long ago died. A visit to an empty tomb, assault upon an Italian nobleman's mansion, duel and execution later, the secret of la Gioconda's smile is (possibly) revealed.