Armand Gamache is the head of the homicide division for the Sûreté du Québec. He is a highly observant and empathetic investigator in his mid-50s who carries a pronounced scar from a recent, botched hostage raid. He relies on psychological profiling to solve crimes and stands firmly against institutional corruption within the police force.

Jean-Guy is Gamache’s ambitious and athletic second-in-command. He is currently enjoying a period of newfound domestic happiness while maintaining his sobriety after a struggle with painkiller addiction. He prefers concrete facts over psychological theories and fiercely idolizes his commanding officer, though he carries lingering emotional vulnerabilities from a recent shootout.

Dom Philippe is the abbot of the fictional Saint-Gilbert-Entre-les-Loups monastery. He is an older, traditional man who believes the monastery must remain isolated from the modern world. He is deeply protective of his community and feels directly responsible for the tragedy that has struck his flock.

Frère Matthieu was the monastery's prior and its highly talented choirmaster. He was instrumental in creating the viral recording of the monks' Gregorian chants that brought international fame to the reclusive order. His desire to release a second recording and break the vow of silence created deep divisions within the community.

Chief Superintendent Sylvain Francoeur is Gamache’s direct superior and longtime rival within the Sûreté du Québec. He resents Gamache’s popularity and anticorruption efforts. Francoeur uses psychological manipulation to assert his dominance and immediately seeks to exploit the vulnerabilities of Gamache's team during the investigation.

Frère Luc is the youngest monk and the newest arrival at the monastery. He possesses an extraordinarily beautiful singing voice and was recruited specifically for the choir. He spends most of his time isolated near the front entrance, obsessively studying chant notation and struggling to fully commit to the broader monastic community.

Frère Simon serves as the abbot’s personal secretary. He is a quiet, observant man who first discovered the prior's body while tending to the abbot's private garden. He remains deeply protective of the abbot and is highly hesitant to share information with the outside police.

Frère Antoine is a young monk who firmly supported the prior's desire to release a second CD and engage with the outside world. He shares a love of hockey with Beauvoir, making him one of the more relatable figures for the police. He views the abbot as a weak leader clinging to outdated traditions.

Frère Charles is the monastery’s doctor, running a surprisingly modern and well-stocked infirmary. He refuses to take sides in the community's internal dispute over the recordings, viewing himself as a neutral healer. He is highly observant of both physical and psychological distress in his patients.

Frère Sebastien is a Dominican friar from Rome representing the Congregation of the Doctrine of the Faith. He arrives unannounced, ostensibly to look into the circumstances surrounding the murder. He possesses sharp investigative instincts that rival Gamache's own detective skills.

Annie is Armand Gamache's adult daughter. She provides emotional stability and open communication for Beauvoir, though they keep their relationship a secret from her parents. She understands the demands of police work, having grown up watching her father leave for sudden cases.

Reine-Marie is Armand Gamache's wife. Though she is not physically present at the monastery, she serves as her husband's primary emotional anchor. Gamache regularly writes her letters to process his thoughts on the investigation.

Captain Charbonneau is a local Sûreté officer who guides the investigative team to the remote site. He is intimidated by Gamache but highly respects the legendary inspector's reputation for fighting corruption.

Frère Raymond is the abbey’s engineer and building manager. He is acutely aware of the structural damage threatening the monastery and strongly supported the prior's plan to fund necessary repairs with a new CD. He becomes frightened during intense police questioning.

Frère Bernard is an older monk who strongly supports the abbot's traditional leadership. He provides the police with historical context about the community's reliance on the abbot's final authority and the internal divisions caused by the recording.