Much of the action of this short novel takes place in the rickety old stage-coach — or coucou — of Pierrotin, which regularly carries passengers and goods between Paris and Val-d'Oise. On one such trip from Paris, Comte Hugret de Sérizy, a senator and wealthy aristocrat, is travelling incognito in order to investigate reports that Monsieur Moreau, the steward of his country estate at Presles, is being less than honest in his dealings on the count's behalf with a neighbouring landowner Margueron, a piece of whose land the count wishes to buy. Among the count's fellow passengers is Oscar Husson, a young good-for-nothing mummy's boy, who is being sent to a friend of his mother's Monsieur Moreau in the hope that a position can be found for him.
