A hail of bullets interrupts a period of dead calm. An elderly brother and sister open fire on the plaza below their apartment, punishing the people of Vigata for their sins. News cameras film Inspector Montalbano--gun in hand--scaling the building to capture the pair of unlikely snipers. The inspector is hailed as a hero, but soon begins to receive cryptic messages in verse from someone challenging him to go on a "treasure hunt." Intrigued, he accepts, treating the messages as amusing riddles--until they take a dangerous turn.