This third programme in the series on Leonardo da Vinci begins by stating that the Mona Lisa is the most famous image in the history of art - but how and why has it become so famous? To answer this, we begin by examining the history of painting. Presenter Alan Yentob, travels to the Loire Valley, France, where in 1516 Leonardo entered the court of King Francis I, bringing the Mona Lisa with him. Alan is amazed to discover that the King kept this priceless painting in his bathroom. We follow the journey of this painting as it passes through the possession of the French Royal Family to Napoleon, for whom it was a favourite, until the revolution in 1789 when it entered the Louvre.