A more curious, more filled in and filled out Simenon featuring two Maitres--not only the master but also, as properly addressed over there, a lawyer who, even after he was disbarred, presided over the affairs of a wealthy old woman. The spinster is her young niece whom she (mal)treats as a domestic, and the niece is greatly alarmed by a nocturnal visitor before both women die, hours apart. There's also a visiting American studying la methode Maigret which as you know is a combination of good food and drink, psychology, and sudden inspiration. This is the original Simenon (1942 copyright) who converted petit, petit bourgeoisdom into a world all his own.