In 1822, Toussaint Rouveyre, a former captain in Napoleon's army, returned to his village in the Ardèche after the defeat at Waterloo and a seven-year stay in America. There, he reunited with his family, persecuted by the Restoration regime. In order for his father to give him his share of the inheritance in advance of his permanent move to America, he needs the consent of his younger brother Antoine, a carpenter who is on the Compagnons' Tour de France. When Toussaint learns that his brother, a member of the Compagnons du Devoir (Devoirants) association, has been killed by a companion from the rival association, the Compagnons du Devoir de Liberté (Gavots), he is determined to find the murderer, a certain Tourangeau Sans-Quartier, and avenge his brother. To find this man, he joins the Compagnons du Devoir de Liberté incognito.