Police inspector Guy Decomble is sent out to deal with pilfering from a market. On his way, he finds a man who has just been shot by three men in a car. When he goes to find help, another car picks the injured man up. Then Decomble is grabbed by the shooters, Americans who question him and beat him unconscious. In his third appearance as Maigret, Jean Gabin has only a pair of American sunglasses to lead him to the answers.
It's clearly a programmer, taking advantage of Gabin's excellence and Georges Simenon's unlikely detective stories -- this is adapted from one of them. Still, Gabin puts in a fair day's work. He's one of those performers, like Ann Sheridan, who are clearly concentrating on whatever they are doing at the moment, whether it's bussing dishes or removing the band from a cigar. Gabin's Maigret is a man who asks questions, gives orders, and that's it. It may seem barebones, but one of the reasons I stopped reading Simenon's books is that his Maigret is exactly the same.
All this results in a tight movie with a mystery which makes so little sense that only Maigret can figure it out. At least, he says he has it figured out before having someone else explain.