In August 1939, curators at the Louvre nestled the world's most famous painting into a special red velvet-lined case and spirited her away to the Loire Valley as part of the biggest museum evacuation in history. As the Germans neared Paris in 1940, the French raced to move the masterpieces still further south, then again and again during the war, crisscrossing the southwest of France. Throughout the German occupation, the museum staff fought to keep the priceless treasures out of the hands of Hitler and his henchmen, often risking their lives to protect the country's artistic heritage.