Armand is the head of homicide for the Sûreté du Quebec. Known for his patience, active listening, and disdain for guns, he is an unconventional detective who prioritizes compassion over force. Despite his calm exterior, he struggles with deep-seated anger toward those who harm his family, and he faces a challenging case that tests his faith in his colleagues and the institution he serves.

Jean-Guy is Armand's second-in-command and son-in-law. Having overcome past addiction issues, he is fiercely loyal to Armand and tries to emulate his father-in-law's gentle, methodical approach to policing, though he naturally leans toward a more aggressive style. He travels extensively during the investigation, pursuing leads from Montreal to Washington, DC.

Isabelle serves as Armand's co-second-in-command at the Sûreté du Quebec. She provides a grounded, impartial perspective to the team's brainstorming sessions and is not afraid to question Armand's assumptions. Her role in the investigation takes her on a crucial trip to Rome to interview church officials.

Jeanne is the executive assistant to the deputy prime minister and a formidable adversary to Armand. She previously framed his son for a crime, earning Armand's lasting wrath. A highly connected political aide, her current motives remain opaque as she initiates contact with Armand through a series of cryptic messages and proxies.

Dom Philippe is the abbot of the fictional Gilbertine monastery Saint-Gilbert-Entre-les-Loups. Born Yves Rousseau, he is a deeply spiritual and calming presence who leaves cryptic clues for Armand in Three Pines. His sudden disappearance from his monastery raises urgent questions about his safety and connections to a growing conspiracy.

Reine-Marie is a 57-year-old senior archivist at the Bibliotheque et Archives nationales du Quebec. As Armand's wife, she provides a vital emotional anchor and acts as his confidante for all his cases. She organizes the extended family's stay in Three Pines to keep them safe while Armand investigates potential threats in the city.

Charles is a 27-year-old marine biologist working for Action Quebec Bleu. A former addict who recently became sober, he volunteers at a local shelter and maps out pollution in Canadian lakes. His attempts to warn Armand about compromised law enforcement agents place him in extreme danger.

David is the assistant commissioner of the Royal Canadian Mounted Police. Having aided Armand in the past, he is privy to high-level intelligence regarding national security and terrorism. Armand turns to him for help analyzing threats to infrastructure, though David advises caution about alerting the public.

Marcus Lauzon is a powerful Canadian politician who recently became the deputy prime minister. He controls both the Environment and Industry, Trade, and Commerce portfolios, giving him immense influence over Canada's natural resources and infrastructure.

Ruth is the eccentric, foul-mouthed poet laureate of Three Pines. Known for carrying a pet duck and dispensing harsh but sometimes profound advice, she provides childcare assistance when the Gamache family home becomes crowded with grandchildren.

Frere Simon is the secretary to the abbot at Saint-Gilbert-Entre-les-Loups. Left in charge after Dom Philippe's sudden departure, he is a secretive Gilbertine monk who routinely opens and reads the mail meant for other brothers, making him a reluctant but useful source of information for the police.

Sebastien is a Dominican monk and former teacher at a seminary in Washington, DC. He is one of three clergy members disciplined for singing karaoke in their robes. His intense passion for environmentalism and secretive correspondence draw the attention of the Sûreté during their investigation into ecclesiastical mysteries.

Sister Irene is a Dominican nun originally from Cleveland, currently working in the Office of the Doctrine of the Faith in Rome. She shares a history with Sebastien and Robert from their seminary days in Washington, DC, and possesses crucial information about a looming threat.

Brother Robert is a timid Carthusian monk who resides at a monastery in France. He is one of only two people who know the complete recipe for the chartreuse elixir. He goes into hiding after learning of a terrifying plot during a confession.

Shona is a prominent vlogger who harbors a deep, public grudge against Armand Gamache. She blames him for the arrest and subsequent death of her mother in prison, dedicating her platform to destroying his reputation.

Claudine is the fiercely protective director of an unhoused shelter in Montreal. She initially conceals her title to gauge the detectives' intentions but eventually aids them by providing access to Charles's belongings and the shelter's security footage.

Raymond is the only living brother of Yves Rousseau (Dom Philippe). Living in the remote town of Blanc-Sablon, he is highly suspicious of strangers after his brother visited him to warn of impending danger and borrowed his identification.

Manon is a junior sanitation engineer working at the Charles-J.-Des Baillets water-treatment plant. Although she lacks high-level access, she is uncorrupted and resourceful, guiding the detectives through the facility's complex emergency protocols.

Evelyn is the head of Organized Crime at the Sûreté du Quebec. She is skeptical of Armand's theory that two recent, identical murders are connected to the Mafia, leading Armand to question whether she is merely incompetent or actively compromised.

Goudreau is the head of the Highways division at the Sûreté. He is known for being inept and disruptive during meetings, leading his colleagues to view him as a bureaucratic nuisance.

Daniel is Armand and Reine-Marie's son. He has a history of drug addiction and recently completed rehab after a traumatic stint in prison engineered by his father's enemies. He maintains deep trust in his father despite being kept in the dark about current threats.

Annie is Armand's daughter and Jean-Guy's wife. She balances raising her children with supporting her husband and father through the stress of their dangerous investigations.

Claude is the former head of the Paris police. As a trusted old friend of Armand, he leverages his local authority and expertise to escort Isabelle safely to a remote Carthusian monastery.

Whitehead is the former chair of the Joint Chiefs of Staff for the United States. He is a highly placed contact of Armand's who provides sobering intelligence on the catastrophic societal impacts of attacks on public infrastructure.

Brother Constantine is a monk at Grande Chartreuse who holds the second half of the secret recipe. He possesses crucial hidden documents left behind by his colleague.

Olivier co-owns the local bed and breakfast and bistro in Three Pines. He provides Armand with critical clues about a secretive guest who left behind a rare bottle of alcohol.

Gabri is the co-owner of the Three Pines bed and breakfast. He helps identify the mysterious guest by recalling the man's pleasant singing voice.

Myrna is a retired psychologist and the owner of the local bookshop in Three Pines. She is part of the close-knit community that provides a safe haven for Armand's family.

Margaux is the executive director of Action Quebec Bleu. She oversees investigations into lake pollution and provides Jean-Guy with information regarding Charles's recent assignments.

Gauthier is an RCMP officer stationed on duty in Ottawa. He becomes entangled in the high-stakes pursuit led by Armand and Jean-Guy after receiving orders from his superiors.