Could the complex ways these three lives intertwine hold the key to a historical riddle as enigmatic as the Mona Lisa's smile -- why Leonardo da Vinci devoted three years to a painting of the second wife of an unimportant merchant when all the nobles of Europe were begging for a portrait by his hand?

Only a master storyteller like two-time Newberry Medal-winner E.L. Konigsburg could create such an intriguing answer to the puzzle behind the most famous painting of all time.