Inspector Maigret comes home to lunch one day to learn that a strange young man has visited Maigret's home, hoping to see him, but then disappeared--taking with him the Inspector's souvenir-revolver from the FBI in America. Who is the youth? Why did he want the gun? Could he be connected to the case of strange, ill ""Baron"" Lagrange, a small-time entrepreneur who has been linked to the murder of politician Andre Delteil? (Lagrange was seen carting Delteil's body around in a trunk.) Yes, indeed: it eventually becomes clear that the youth is the son of pathetic, desperate Lagrange--and that he is bound on some sort of revenge-quest against his father's enemy, a seductive con-woman whom the youth follows to London's Savoy Hotel. . . with Maigret hot on his heels. Maigret suavely prevents the boy from killing his quarry; he also reveals the blackmail set-up that led to Lagrange's hapless involvement in the death of Delteil. Short, unusually structured, with a disturbing portrait of the unfortunate Lagrange: satisfying, offbeat Simenon.