This "Duo" is made up of Gabriel, a super good cop, a retarded teenager, single, whom fate sticks with Carole, a gendarmette, mother of a family, charming, but frustrated. She is married to the judge responsible for their investigations, Jean-Louis, an obsessive jealous. Gabriel is the adopted son of the city's mayor, Max, who is at the same time the godfather of the local mafia. Gabriel obtains decisive information from Max to advance his investigations. Max, meanwhile, uses Gabriel to settle scores with his competitors. The unit of Gabriel and Carole is directed by Axel, an incompetent cop, poet, infatuated with a journalist for whom he is ready to plant all the investigations. And there is also Gédéon, tax expert, computer ace, 12 years of mental age, who loves a transvestite prostitute to whom he hopes to pay for an operation to make him an honest woman.