On a stormy evening in the coastal town of Concarneau, Monsieur Mostaguen, a local wine-merchant, is shot after leaving the Hôtel de l’Amiral. When Inspector Maigret is called in to solve the crime he finds the townspeople in a state of panic, provoked by inflammatory articles in the press, as one by one prominent citizens of the town are attacked. But what connects the victims? What is Emma, the downtrodden hotel waitress, hiding from Maigret? And what is the significance of the mysterious yellow dog lurking around Concarneau, causing its citizens great unease?