Commissaire Georges Dupin is certain these first beautiful summer days in June would be perfect for a fun trip to Saint-Malo. In a region known as the culinary heart of Brittany, the paradoxical city is known for being a uniquely Breton, yet un-Breton, place. Their cuisine's moto is voyages et aventures. Travel and adventure. Dupin would love to explore the internationally renowned cuisine one bite at a time. But to his chagrin, Dupin is there instead to attend a police seminar dedicated to closer collaboration between the Breton départements.
To prepare himself for what's to come while in Saint-Malo, Dupin wanders through the halls of a local market while admiring its aromatic orchestra. But Dupin's morning is derailed when there's a murder at a nearby stall. He quickly realizes this case is unlike any he's worked on before. The police know the victim: Blanche Trouin, a chef of the region. They know the perpetrator: Lucille Trouin, Blanche's sister and fellow chef in the area. The two had a well-known feud. After a bit of searching, Lucille is in custody. The only thing they're missing is the motive. And Lucille refuses to talk.
Saint-Malo doesn't want help from the visiting commissaires. Even Dupin's assistant is telling him to stay out of it. But Dupin, along with a few of his colleagues, can't help but begin an investigation.