Coup dur chez les mous (1956)

Ernest is an honest sales representative .He accidentally swaps his suitcase for that of gangsters who have just burglarized a jeweler store .The policemen,who wanted to catch the robbers in the act, find a suitcase full of brushes and Ernest is arrested.Gigi,the gangsters' moll , mistakes him for a tough guy and helps him to escape from jail.He reluctantly becomes the thieves' boss.