An old school friend of Maigret's appears in his office. Léon Florentin was the class clown. He's still making faces, but at fifty-four years old it's not so amusing anymore. Especially since he has just come from the apartment of his murdered mistress.
In addition to Florentin, Josée had four lovers, none aware of the others. Only Florentin had a key to the apartment and an overview of the goings-on.
When one of the lovers shows up unannounced one afternoon, Florentin hides in a closet. He hears a shot, eventually comes out of hiding, and finds his mistress dead. Anyway, that's his story. But he always was a liar.
As Maigret interviews the lovers, he gets acquainted with the victim: a kind, warmhearted woman with a well-bred air, above all a discreet woman who would happily listen to a man's troubles for hours. She was also a gifted liar.
How to get at the truth? The concierge, a vast mountain of flesh with expressionless eyes, must know something. But she won't tell.
Simenon's wry descriptions of the wily Florentin, the frightened lovers, the grim concierge, and the victim's well-organized and lucrative domestic arrangements all conspire to make this an excellent Maigret.