The hero of the novel is the mysterious and distinguished Rodolphe, who is really the Grand Duke of Gerolstein (a fictional kingdom of Germany) but is disguised as a Parisian worker. Rodolphe can speak in argot, is extremely strong and a good fighter. Yet he also shows great compassion for the lower classes, good judgment, and a brilliant mind. He can navigate all layers of society in order to understand their problems, and to understand how the different social classes are linked.