Fred Barker, an unmarried American who remained in France after heroically defending the country during the Second World War, runs the perfume factory in Grasse of his friend Carlo Ferelli, whose life he saved during the conflict. Fred has since adopted a little girl, Cathy. One day, he receives a visit from Félix Mercier, an old man who informs him that he has taken Cathy into his custody and that he will return her to him when Fred finds his granddaughter Hélène, a 17-year-old teenager who accuses the factory of being a front for white slavery. Fred, dumbfounded, sets out to find Hélène, so he can quickly get Cathy back.

The blueprints of an aeroplane built from an ultra-secret metal are stolen from national security. French secret service agent Walder believes that the documents are now in Switzerland, in the hands of a man named Lindbaum. The latter agrees to hand over the blueprints in return for a large sum of money. Another agent, Francis Coplan, is sent to Switzerland to handle the deal, but Lindbaum only has half of the documents because he was double-crossed by Kalpannen, an international crook. With the help of Heidi, a Swiss correspondent, Coplan sets out to identify the members of Kalpannen’s gang, only to find that they have all been murdered…

Cute Sophie is an amoral French girl living in a sumptuous Venetian palazzo. She is the kept woman of a very rich but undesirable fellow named Eric von Bergen, an ex-nazi turned forger.

Arsène Lupin is extremely popular among the population, because he allows the needy to share in his acquired wealth. Before entering the service of the German Emperor Wilhelm II, he removes his vault in Alsace, steals two paintings of old masters, steals valuable gems and calls out to the police prefect to avoid his arrest. But this time he risks being seriously recognized. Lupin must once again use his fine intellect to deftly escape the situation.

Some gangsters use a young girl to get to a recently released convict who hid $10 million from a robbery just before he was caught.