In the fictitious republic of Carvolie, the Council President, Desnoyaux, although he has a nice wife and a daughter, lets himself be bossed around by his mistress, Lulu de Pompadour. In the hands of Lulu, he does not even notice that a party has formed against him. The main conspirators are Gargarousse, Cornillet, General Dubul, Petit-Morin, and Desnoyaux's chauffeur Prosper. One night, Prosper drives the President into a trap where the men kidnap him and keep him prisoner. Meanwhile, other men spot a sewer man who looks exactly like Desnoyaux! He names is Justin Morille, aka "father Lampion", and they offer him to take Desnoyaux's place. With the help of a few drinks, and before he even realizes it, Lampion wakes up in Desnoyaux's bed. After he has reinstated Desnoyaux as a good husband and good father, he launches new laws and reforms. He decides to install loudspeakers in villages to promote good sense and his "gold policy" : each citizen has to give the State a small amount of gold as tax. Unexpectedly, his measures earn him a great popularity. Though he asks Desnoyaux to take his place back, he asks the man to keep acting just like he did. Lampion then goes back to taking care of the sewers, only as a "General inspector", as he promoted himself.