L’Agence O is a famous Parisian private detective firm. Its premises are located in the Passage Choiseul. In front, Torrence leads the shop. In fact, the agency's team is complemented by Émilie le Roux, Mademoiselle Berthe and Barbet, who scrutinize clients through a one-way mirror located behind the desk. Getting hold of a man disguised as an old lady, solving the mystery of the Prisoner of Lagny or discovering who is blackmailing the painter Tigrane Alban does not worry the experts at the O Agency.

Les Dossiers de l’Agence O is a French-Canadian television series in thirteen episodes of approximately 55 minutes created by Marc Simenon and broadcast first in Quebec from December 14, 1967 to March 13, 1968 on Télévision de Radio-Canada, then in France from March 11 to June 3, 1968 on the first channel of the ORTF.