The titular caller is a pathetic creature with a hare-lip named Léonard Planchon. He has been showing up at the Quai des Orfèvres on Saturdays hoping to screw up enough courage to talk to the detective chief inspector about something, but has always chickened out. So instead he decides to go to Boulevard Richard-Lenoir, where Maigret lives, and catch the big guy at home.
This didn’t make much sense to me, but then nothing about Planchon rang true. He’s neither sympathetic nor believable. In today’s Internet manosphere language he’s an exaggerated type of the beta simp: a total loser who marries a hot girl who in turn shacks up with one of his employees, a guy who first supplants him in the bedroom (forcing him to sleep in the kitchen on a camp bed) and then takes over his house-painting business. Planchon wants to warn Maigret in advance that he’s thinking of taking . . . drastic measures. I thought for a while that we might be entering Before the Fact territory, which had the potential to get interesting. But then Planchon disappears.
No prizes for guessing what has happened. And given that the perps are a pair of wild animals, possessed of low cunning but low intelligence, it doesn’t take Maigret long to catch them out. Another weak effort, and a bit silly too.