Arsenio Lupin contro Arsenio Lupin

Jean-Claude Brialy learns he is the natural son of the late Arsène Lupin and goes to claim his inheritance as the heir of the greatest thief the world has ever seen. However, stage magician and thief Jean-Pierre Cassel is also Lupin's son, and the two begin a running competition to see who gets to keep the stolen crown jewels of Poldova. Other interested parties include Françoise Dorléac as Cassel's girl friend, Geneviève Grad as the exiled Princess of Poldova and club dancer, whom Brialy woos, and Michel Vitold, who wants the crown jewels for the cash. The police are present for comic relief.

It's a light-hearted romp as the two half-brothers one-up each other and try to figure out what is going on. It's reminiscent of Maurice Leblanc's tales of the master, although it lacks the elaborately detailed mysteries that provided the skeletons of the novels. Capably directed by Édouard Molinaro (best remembered for LA CAGE AU FOLLE), it maintains its old-time ambience via references to the war in the Rif and costuming.