A killer challenges Larosière: he sends him letters, giving the date and place of his murders, and signed ABC... Larosière and Lampion will have to discover why a mysterious psychopath, who kills alphabetically by name of victim and place and who leaves ABC bus schedules in his path, has fun taunting them...

Jacko Vallabrégue is accused of killing his adoptive mother. While he has just been killed by his comrade in prison, an unexpected witness proves his innocence. Larosière, who had Jacko locked up, takes over the investigation to find the real culprit. But who of Mrs. Vallabrégue's other three adopted children is the perpetrator of the crime, if not Jacko, whom they had all held to be the only possible culprit...

During an exchange of bullets, Lampion was wounded and Larosière decided to send him to the countryside during his convalescence. But this one is not easy because a mysterious crow sends anonymous letters denouncing all the shameful secrets of the villagers. The investigative duo decides to take matters into their own hands when the crow, tired of croaking, begins to kill.

During the first paid holidays, Larosière decided to take a vacation. He is so bored that he is about to leave when he meets a young and very attractive stylist who is sought at all costs to eliminate. The commissioner, delighted to have a business to put in his mouth, decides to protect it and brings in Lampion who is hired incognito as a handyman...

A mysterious murder with no apparent motive was committed near an institution for young girls good chic good kind. And here is our dear Commissioner Larosière and the unpayable Lampion landing in the middle of a band of more or less charming mice in search of a cat that plays on their nerves. Unless the cat in question is simply... one of the mice.

Anonymous letters warn Commissioner Larosière of the impending murder of a wealthy suffragette who is using her fortune to advance the cause of women. But how do you infiltrate a weekend of feminist activists without attracting attention? Disguising Inspector Lampion as a woman seems to be the best solution. Despite his perfect camouflage, Emile Lampion fails to prevent the criminal from striking. His superior then enters the scene. He notes that the organizer of the meeting and her maid have been killed. The daughter who inherits would make an ideal culprit. Louis Servais, trusted man of the murdered lady and especially secret lover of the daughter heiress, does not validate this hypothesis at all...

Emma Vargas was convicted of poisoning her husband, a famous painter and womanizer. But was she really guilty? Without physical evidence or fingerprints, Lampion and Larosière will have to solve the riddle thanks to the different and contradictory accounts of the five main suspects. Reopening a fifteen-year-old business is not easy...

When a popular young girl marries a millionaire who could be her grandfather, and the bad tongues go wild. But when he dies in an arson attack and the family discovers a will in favor of the young widow, the police get involved. The whole family relied on the inheritance and stands as one man against the young woman and against her brother, a disturbing adventurer. Who is the girl really? A white goose or an unscrupulous manipulator?

After a very drunken night, Commissioner Larosière wakes up with the corpse of a young woman in his bed! He has no memory of what happened and realizes with horror that he is now the number one suspect in a murder case. Especially since the girl is a prostitute who worked in a brothel where Larosière had his habits. While Larosière is imprisoned, Lampion struggles to prove his boss's innocence. The commissioner manages to escape, and it is hidden from the Blue Bird (in other words like a rooster in paste!) that he will lead the investigation of Lampion to confuse the real one.

Sacha, 20, escapes from the psychiatric hospital where she was locked up and hides in an isolated house. From the first evening, she is the victim of a terrible hallucination: she has the vision of the body of a bloodied woman at the bottom of the stairs. Has the house been the scene of an atrocious drama or is Sacha taken over by his bouts of dementia? What is the link between the murder of a woman not far from there and the presence in the region of this very disturbed young woman? It is Inspector Lampion's new passion for psychoanalysis that will allow Commissioner Larosière (yet very skeptical about the meanders of the unconscious!) and his assistant to unravel the threads of this strange affair.

Larosière is surprised to see his daughter, Juliette, who has run away from her mother's home, complaining of suffocating under her thumb. The commissioner does not see his arrival with a good eye because a young girl has just been brutally murdered in a theater. Larosière and Lampion find themselves immersed in the universe of a troupe of actors, with its jealousies and its hatreds. Larosière finds with delight the star who enchanted her youth, Sarah Morlant. But when the main actor of the play is found dying, a knife stuck in the back of the neck, the case thickens. The commissioner is obliged to replace him at short notice in the role of Dom Juan, which is not to displease this ham...