The film is set during World War I, as Paris is expected to fall to the Germans. The Princesse de Bormes, a widow, helps wounded soldiers by evacuating them from the front and bringing them to her villa in Paris for medical care. However, the authorities will not give the Princess and the soldiers passes to return to Paris. The situation changes when an innocent 16-year-old boy, Guillaume Thomas de Fontenoy, joins the authorities and is mistaken as the nephew of the popular General de Fontenoy. Thomas is able to use his position of posing as the general's nephew to cut through the red tape, in order to help the Princess. She is entranced by Thomas, and her daughter, Henriette, falls in love with him. However, Thomas feels impelled to see more war action. Later, he is caught behind enemy lines when he is moved with a military unit into the heat of battle.
Source : Wikipedia