Leonardo da Vinci is considered by many to be one of the greatest artists who ever lived. Yet his reputation rests on only a handful of pictures ? including the world?s most famous painting, the Mona Lisa. As the National Gallery in London prepares to open its doors on a remarkable exhibition of Leonardo?s work, Fiona Bruce travels to Florence, Milan, Paris and Warsaw to uncover the story of this enigmatic genius ? and to New York, where she is given an exclusive preview of a sensational discovery: a new Leonardo.