The O Agency, whose exploits, which began last Monday, will be recounted in thirteen weekly episodes, was born in the imagination of Georges Simenon. It is led by two detectives: Joseph Torrence and Emile, a shy-looking young photographer. Today, it is in a Turkish bath, where he is undergoing weight loss, that Torrence investigates. He meets a famous lawyer, Mr. Duboin, and a gangster wanted for two years by the police. A few minutes later, the latter will be assassinated ...

Agency O is commissioned by an insurance company to investigate a series of burglaries that the police attribute to a black jacket that moves on a powerful motorcycle. In his office, Inspector Torrence is examining an object he found, during an investigation, in a jewellery store and whose nature and function are difficult to specify. Then a young brunette girl enters who comes to entrust Torrence with an important document. When the young girl leaves the agency, the object has disappeared...

Did Doctor Maupin poison Madame Goron? In any case, this is what his niece suspects, who calls on the O Agency. When the aunt dies, everything seems to overwhelm the doctor, who nevertheless has an indisputable alibi: he was being watched by the agency! How could he have transported the corpse? Unless the Agency was deliberately put on the wrong track ...

A series of tragic coincidences led the team of the O Agency to investigate in Montigny-sur-Long where, in two inns in the region, two blind travellers were strangled in two rooms, each bearing the number 9. For eight days, the official police are trampling. For fun, Emile begins to research. Torrence moves to the Auberge de la Vane-Rouge. Barbet photographs the clients ...

The O Agency finds itself in Cannes to help "Grandmother" find a seducer and thief of mink coats.

Much to the chagrin of the official police, members of the O Agency are crossing the legal line widely - and repeatedly - to prevent a saxophonist from being charged with murder. They manage - but with difficulty - to establish proof of the plot aimed at compromising the musician.

José is a saxophonist in a nightclub run by a manager nicknamed "The Banker". Kikou, the mistress of "The Banker" also works in this nightclub as a stripper and also prostitutes herself with large clients. José is attracted to Kikou and she is not insensitive to the young man. Having surprised them, "The Banker" decides to take revenge ...

Shot by a gun, a client comes to die in the offices of the O Agency. He is a comfortable bourgeois from Saint Etienne who was due to marry his son the next day. The only clues: a metro ticket, and in his pocket a large revolver that was used a short time ago. But why did he regularly receive boxes of watercolors in the mail when he wasn't painting? When his last words, more or less intelligible, are finally understood, the evidence stands out.