At the remote lake, Vivienne tests the water and records an abnormally high pH, signaling an alkaline anomaly. She and Lacoste make camp, unsettled by the silence. Vivienne worries that someone has been tampering with the water. They mark the site and prepare to search farther in the morning.

In the Gamache home, Caron meets with Gamache and Reine-Marie. Caron apologizes to Reine-Marie, who refuses to forgive her. Gamache says that he believes someone framed Marcus Lauzon and suggests that Frederick Castonguay, Caron’s assistant, may have planted evidence. He secures Caron’s promise to alert him if Castonguay makes contact. Gamache then tells Beauvoir to bring Lauzon to Sunday lunch.

Investigative journalist Shona Dorion, undercover at Action Québec Bleu (AQB), an environmental group, texts Gamache to arrange a breakfast meeting. At AQB’s office, her boss, Margaux Chalifoux, flags a funding detail that Shona misreported. In Three Pines, Gamache asks Ruth Zardo to drive him to Montréal; she agrees and plans to bring her duck, Rosa.

At the lake, Lacoste and Vivienne speak in low voices about the strange quiet. Vivienne connects the high alkalinity to potassium and wood ash.