One day, commissar Maigret is called to investigate a pretty strange death. Louise Voivin was found poisoned in her apartment in the Boulevard Beaumarchais, with a dose of digitalis. Maigret interrogates Ferdinand Voivin the husband of the victim who is 37 years old and a gem dealer and Nicole Lamure, 18 years old the sister of the deceased, who has been living with them. The poison was found in the house in a packet marked “bicarbonate of soda”. Both Nicole and Ferdinand deny having killed Louise, even if they admit that they are lovers. The commissar also finds out that Louise discovered their affair 6 month ago and, since then, the three of them have been living together in a strange way: the deceased only communicated with her sister by written notes, Ferdinand slept on the couch and Louise used to spy everything they did. Also, Maigret discovers that Ferdinand was the one who bought the digitalis during a trip to Netherlands. When he thinks that he finally has the criminal, the situation takes a strange turnover as it is revealed that Ferdinand was very stressed with the situation in his life, being caught between two women who were sisters and that he was thinking of killing himself. If he didn't do it, then, what happened? Did the sister commit murder, did the deluded woman committed suicide or the death was just an unhappy accident?
This report prepared by Dana Samson