A young man is accused of the murder of a great fashion designer. But when he is about to be brought before justice, Moulin is seized with doubt. What if, despite an accumulation of overwhelming evidence, he was not guilty? Moulin, almost lonely, then embarks on an investigation against the tide. And he is not at the end of his surprises.

A young couple of Vendée hoteliers came to Paris to open a restaurant in Montmartre. Subjected to a racket by a gangster organization, they refuse to pay and their restaurant is plasticized. It is Commissioner Moulin who is investigating. Soon, he discovers the head of the organization but the hardest part will be to indict him because the man knew how to take shelter. The young policeman and the clever and devious “white-collar mobster” clash.

By a friend, Commissioner Moulin has just been informed of the strange case of Monique Frémont, a woman who seems to be in a permanent state of terror. A few days later, Monique Frémont is found murdered near the Bois de Boulogne. The investigation was entrusted to Commissioner Le Marchand, a colleague of Moulin ...

Floquet, a wealthy entrepreneur and follower of a religious sect, was killed by the collapse of the vault of a chapel. The investigation takes us into a mystical, silent, strange world, dominated by the personality of the high priest Cassius. For the latter, Floquet was the victim of a "return shock". Commissioner Moulin, flanked by the superstitious Guyomard, tries to understand the incomprehensible.

Wanting to correct a miscarriage of justice, Commissioner Moulin came up against the hierarchy. Responsible for finding a former boss of the underworld, Joseph Braun, escaped from the prison where he was serving his sentence for a murder that he refuses to acknowledge, the policeman takes sympathy for the man and acquires the conviction of his innocence. This understanding earned him a series of setbacks: held hostage by Braun in a bunker, he managed to escape but found himself in prison.

One summer, Moulin is invited by Bulocq, a fisherman by trade, to come and spend a few days of vacation on the island where, as a young boy, he spent his family vacations. During a fishing trip at sea, he brings up the body of Céline Altman, obviously strangled. This murder is followed by that of Snookie, a young woman to whom Moulin became attached ...

Knocks in the walls and floors, objects flying through the rooms, the fire that ignites by itself in the drawers… Do these elements allow us to conclude that a house is haunted? In the absence of specter, it would be a simple case of "small obsession" as the gendarmes record several each year. With one detail: the haunted house is the Norman farm where Moulin spent his youth. The object of persecution is her own aunt, and the teenager at the center of the phenomena is her cousin. The phenomena in question, Moulin and Guyomard see them with their own eyes. Finally, the dead man that we find one fine morning is none other than Moulin's cousin. All this leads the commissioner to conduct the most unusual of his investigations ...

It all starts when a real estate developer is killed in a traffic accident. Crime disguised as an accident? Commissioner Moulin investigates. A lead: Manuel Marchand who had trouble with the promoter following the construction of pavilions. Her granddaughter, after living in the lodge for a year, died. Yet Marchand, a failed actor, has an alibi ...

Nicolas Crescenti, known as "the Twisted", has become the number one public enemy. Superintendent Moulin is on his tracks and, while he is about to arrest him, "the Twisted One" escapes him and injures him. “The Twisted” escapes him a second time during an operation set up by the National Section of Intervention and Research. Moulin then joined the PC. On the racetrack where "the Twisted" must run one of his fillies, the commissioner is organizing a new ambush.

Dure réalité pour Moulin : atteint d'une fièvre carabinée, il est obligé de laisser l'avion de touriste qu'il devait emprunter à son aéro-club. Mais l'homme qui prend sa place est victime d'un accident mortel. Rapidement, il apparaît que l'appareil a été saboté. Quelqu'un en voulait donc à la vie du commissaire. Mais de qui s'agit-il? Malade et perclus de douleur, Moulin va devoir enquêter sans savoir où se diriger. Le voilà embarqué dans une drôle d'affaire, bourrée de fausse pistes et de mystères, qui trouvera sa réponse dans un ultime et dangereux face à face aérien dans le ciel de France…

La jeune employée d'une galerie de peinture est suivie dans le métro par un inquiétant personnage. À la sortie, il la rattrape, la tue et s'enfuit. Un témoin, paisible musicien, est convié par la police à une tentative d'identification. Coup de théâtre, il reconnaît formellement parmi les suspects présentés, le commissaire Moulin! Le criminel serait donc un sosie de Moulin dont le portrait-robot est largement diffusé dans la presse. Le propriétaire d'un petit hôtel de banlieue reconnaît à son tour, sur la photo, un de ses pensionnaires, et la police n'a plus qu'à venir cueillir le suspect…

Le père de Cécile Vierne, une jeune médecin psychiatre, est mort des circonstances étranges. Cécile demande au commissaire Moulin d'élucider ce qui lui paraît être un mystère. le résultat de l'enquête confirme la thèse du suicide. Mais Cécile reste persuadée que son père a été tué. Moulin entame une contre-enquête, assisté d'un commissaire de police de Nice. les voilà bientôt amenés à suspecter un certain Blaireau, qui meurt lui aussi. S'agit-il d'un autre suicide ou d'un autre crime ?

Sept attentats à l'explosif sont commis à Paris. Chargé d'enquêter sur l'un deux, le commissaire interroge Lannelongue, un idéaliste non violent et Rose-Marie Mercier, surnommée « Rom », qui chante dans un cabaret pour payer ses études de violoncelliste. Rom vit entourée d'amis, tous révoltés. L'un deux, José, plus âgé, est un terroriste agissant pour une organisation internationale. Malgré les mises en garde du commissaire, Rom poussée par José passe à l'action.