Maigret goes to Delfzijl, in the Netherlands, as an unofficial representative of the Police Judiciaire, for a French professor, Jean Duclos, from the University of Nancy, is being detained in the case of the murder of Conrad Popinga, a retired sea captain, whose guest he'd been while delivering a lecture on criminology. Popinga had been shot from his bathroom window, as he was returning to his house by bicycle, after seeing home Beetje Liewens, a neighbor. Duclos had heard the shot and rushed into the bathroom, and picked up the gun. A sailor's cap belonging to the seaman Oosting and a cigar butt are found in the house, but Maigret dismisses these as red herrings. In the house at the same time were Popinga's wife, Liesbeth Popinga, her sister, Any Van Elst, an unmarried lawyer, and a maid. Neighbors, Carl Weinand and his wife and children had been there, as well as CornÚlius Barens, a cadet on the training ship Popinga taught at. The Dutch inspector, Pijpekamp, is anxious that the town not be disturbed, and hopes Maigret will agree that a foreign sailor did the crime and left by ship. But Maigret reconstructs the evening, and reveals that Any Van Elst, jealous of Popinga's attention to Beetje Liewens had decided to kill him. Beetje Liewens had been looking for anyone to take her away from Delfzijl. Maigret returns to Paris without being thanked. Any Van Elst later killed herself before the trial, and Beetje escaped Delfzijl to Paris, having married a light bulb salesman.
This report prepared by Dana Samson