The rogue (George Sanders) who would later call himself Eugène François Vidocq is born in a prison cell, the twelfth child of a woman who steals a loaf of bread each time she needs shelter to give birth. As the boy grows into a man, he is constantly in and out of jail. As the story begins, he and his cutpurse cellmate and associate, Emile Vernet (Akim Tamiroff), escape using a file hidden in a birthday cake provided by Vernet's aunt Ernestine (Gisela Werbisek).