"They killed him. It was bad money. I told him no", Benedetta Toso gasps the words about her recently-deceased husband, Vittorio Fadalto. Brunetti promises to look into the matter. Fadalto had worked in the field collecting samples of contamination for a company that measures the cleanliness of Venice's water supply. And Brunetti soon comes to realize the perilous meaning in the woman's accusation and the threat it reveals to the health of the entire region. The 29th novel in Donna Leon's bestselling crime series.