The Mysteries of Paris tells of the fight between good and evil set on the streets of French capital in the mid 19th century. The hero of the novel is the enigmatic and distinguished Rodolphe, who is really the Grand Duke of Gerolstein, 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. Rodolphe is accompanied by his friends Sir Walter Murph, an Englishman, and David, a gifted black doctor, formerly a slave. The antagonist and the representative of evil is Ferand, a lawyer and delegate of a new commercial order.