Louis Mennechain is a modest locksmith. So imagine his amazement when Professor Piétrefond approaches him and tells him he recognizes in him a descendant of the kings of France, more precisely of Louis XVII (the king who never reigned). According to him he is none other than the monarch's great grandson. Louis's life is soon turned upside down as he becomes the center of attention of a group of ardent royalists. Even a duchess "gives" him her love to make sure that he accepts his role as pretender to the throne...
During the Second World War, Georges Masse undergoes a dangerous mission by taking secret documents from Tangiers to London.
Hélène, a young waitress working in a bar frequented by German soldiers, saves the life of Pierre, a Resistance fighter. Her jealous lover has her arrested first and then released. Later on, Hélène is wounded while walking in the streets. Pierre has her transported to friends with the hope of taking her to London with him. Unfortunately, owing to lack of space in the plane, Pierre has to fly alone. Hélène has to wait several weeks before being able to board a new plane. When the day comes at last, the Germans are waiting for the plane on the clandestine airfield.