Maigret and the headless corpse

When a man’s arm is fished out of the Canal Saint-Martin in Paris, Maigret and his colleagues are puzzled. A woman’s arm they would understand as the work of a psychopath or a man’s body as a gang related killing, but they are even more puzzled when the rest of the man, minus his head, is dug out of the Canal. Maigret’s attention turns to Madame Calas, a strange woman running a bistro along with her husband near the canal. The husband is away in the country, Madame Calas willingly sleeps with anyone who asks (Maigret does not test this theory) and the judge soon arrests her, her lover (the main one), and a young delivery boy (also a lover). But Maigret is not satisfied and pushes further and uncovers a story, and a motivation for murder, that is far stranger than anything he has ever seen before.