Gamache and his team review Langlois's second notebook before dawn in Three Pines and realize the poisoning plot was only a diversion.

Corrupt Chief Inspector Tardiff receives a secret call from mob boss Moretti, who demands to know if Gamache is still a threat.

Beauvoir finds Gamache in the basement of St. Thomas's Church, secretly examining Langlois's marked map of Québec.

Gamache recruits biologist Dr. Vivienne LaPierre for a field mission and splits the team to investigate the remote lake and the prison.

Gamache meets secret informant Shona Dorion at a Montréal diner, where she reveals money laundering and 'FEDS' references in AQB's files.

Lacoste and Vivienne uncover Frederick Castonguay's body in a shallow grave, wrapped in a green garbage bag, at the remote lake.

Gamache stages a tense Sunday lunch at his home, bringing Lauzon and Tardiff together as a psychological test.

During the Sunday lunch, Lauzon fakes a stumble and whispers 'FEDS' into Gamache's ear, ensuring Tardiff cannot hear.

Gamache returns to the remote lake, realizes the carved arrow points upward, and Lacoste retrieves Langlois's hidden laptop from the tree.

Nichol unlocks the laptop and finds a file containing IP addresses for dark-web '.family' sites spreading anti-Canada disinformation.

General Whitehead meets Gamache at the Haskell Opera House and reveals 'War Plan Red,' a secret US plan to invade Canada for water.

General Whitehead is shot at the White House, and the Canadian Parliament is immediately placed under lockdown.

Gamache deliberately shouts 'War Plan Red' to provoke Prime Minister Woodford into a violent outburst that Shona livestreams to journalist Paul Workman.

Captain Pinsent's team raids the Mont-Laurier airfield and rescues Lacoste and Shona, stopping the incendiary bombers from launching.

Lacoste's photograph from Chalifoux's basement provides the evidence needed to arrest Prime Minister Woodford as the conspiracy's true mastermind.

The Black Wolf opens with Chief Inspector Gamache uncovering that a thwarted water poisoning was merely a diversion for a larger international conspiracy. Working with a small, trusted circle, Gamache follows cryptic clues left by murdered biologist Charles Langlois — a marked map and a hidden laptop — to expose a dark-web disinformation network and a shadowy chain of organized crime and government corruption. A staged Sunday lunch and recovered digital evidence lead Gamache to General Whitehead, who reveals a secret US plan to invade Canada for its water resources under the codename War Plan Red. When Whitehead is assassinated and Parliament is locked down, Gamache orchestrates a public confrontation with Prime Minister Woodford that goes viral. A dramatic rescue at the Mont-Laurier airfield stops the incendiary bombers, and a photograph from a conspirator's basement finally provides the evidence needed to arrest Woodford as the true mastermind.

The headline events of Gamache's investigation into the black wolf conspiracy.

Clara Morrow stares at an unfinished canvas in her Three Pines studio, struggling with her new series titled Just before something happens…

Ruth Zardo startles Beauvoir from a church pew as he searches for Gamache in St. Thomas's Church.

Reine-Marie studies Langlois's map and spots a small arrow indicating movement north into Canada from Vermont, not away from it.

A Sûreté officer pulls Beauvoir over for speeding and insists the poisoning plot was staged and that Gamache is the real villain.

Lauzon refuses to speak to Beauvoir and demands to see only Chief Inspector Gamache when interrogated at Archambault penitentiary.

Lacoste and Vivienne find a river rock deliberately placed at a tree and discover an arrow carved with the initials 'cl' in the bark.

Gamache realizes his hearing has partially returned at the Ritz-Carlton and quietly asks Ruth to keep the recovery a secret.

Reine-Marie, Clara, Myrna, and Ruth visit a museum in Jericho, Vermont, and discover Camp Ethan Allen aligns with Langlois's map line.

Ruth warns Reine-Marie about social media posts claiming Canada plans to attack the United States, invoking Animal Farm as a cautionary parallel.

Lacoste finds a childhood class photo at Castonguay's family home proving Castonguay and Langlois were once best friends.

Gamache and Lacoste travel to Ottawa and present the laptop evidence to Prime Minister Woodford, who dismisses their warnings as alarmist.

A senator fakes a medical emergency as a diversion, giving Gamache and his team cover to break out of the Parliament holding room.

Beauvoir and Nichol follow Lauzon's guidance and rescue Tardiff from a mob execution in the flooded Mont Royal caves.

Gamache publicly testifies in Ottawa naming Lauzon as mastermind while privately continuing to pursue Woodford as the true villain.

Clara opens a Montréal museum exhibition featuring a portrait of Woodford just before his arrest, displayed beside a painting of a melting snowflake.

While Gamache's core team pursues the main conspiracy, a web of secondary characters and quieter discoveries steadily deepen the investigation. Artist Clara Morrow's creative struggle and Ruth Zardo's sharp observations frame the story's atmosphere of dread, while Reine-Marie's archival instincts and a Vermont road trip uncover critical geographic clues the team nearly missed. Beauvoir's encounter with a conspiracy-believing Sûreté officer and Lauzon's stubborn prison silence reveal how thoroughly disinformation has already poisoned institutional trust. Field discoveries at the remote lake, a childhood photograph, and Ruth's Animal Farm warnings each provide breakthroughs that shift the investigation in new directions. As the crisis peaks inside a locked-down Parliament and on the streets of Montréal, characters from Tardiff to Clara play unexpected roles in bringing the conspiracy to light and justice.

Supporting discoveries and secondary moments that shape the investigation.

Gamache is haunted by biologist Langlois's dying word 'family' and fears the 'black wolf' of hate remains at large after the poisoning.

Agent Nichol secretly sends encrypted texts from inside Tardiff's office to Moretti, revealing her role as a double informant.

Gamache summons former adversary Jeanne Caron to Three Pines and questions her about Langlois and the vanished Frederick Castonguay.

Reine-Marie drives to the Québec-Vermont border, sees a sign for Jericho, and confirms that Langlois's map line points directly there.

Vivienne's water tests at the remote lake reveal an abnormally high alkaline pH level, later attributed to ash from recent megafires.

Gamache pulls Tardiff aside after the Sunday lunch, and she admits to being a deep-cover informant inside Moretti's criminal organization.

Beauvoir meets General Whitehead in a Washington, DC diner, and Whitehead reveals that 'FEDS' stands for Fire Event Detection Suite.

Lacoste identifies the unknown woman photographed with Moretti as Margaux Chalifoux, the AQB director, linking organized crime to the environmental front.

Gamache stages a public arrest of journalist Shona Dorion to safely extract her from AQB and secure her as a covert ally.

Studying the White House security footage, Gamache notices that Manon Payette reacts with foreknowledge, not shock, to General Whitehead's shooting.

Lauzon tells Beauvoir during a prison interrogation that Jeanne Caron, not himself, orchestrated the frame-up and is running the current operation.

Defense Minister Trudel reveals that Manon Payette is actually Marie Lauzon, Marcus Lauzon's daughter, embedded at the center of political power.

Marie Lauzon draws a pistol on Gamache in Parliament's sub-basement then hands him a dossier identifying the true conspirators.

Gamache flies to Suffolk and meets UK intelligence chief Sherry Caufield, who confirms Prime Minister Woodford is the true 'black wolf.'

Gamache and Reine-Marie sit in their garden a year later, aware the water crisis persists and the threat of future conflict remains.

The Black Wolf is driven by a series of revelations that reframe everything that came before, beginning with Gamache's intuition that a dying biologist's final word was a clue rather than a farewell. Double-agent Nichol's secret communications, Caron's reluctant return as an ally, and Vivienne's scientific findings at the remote lake each redirect the investigation in ways no one anticipated. The Sunday lunch confrontation with Tardiff, Whitehead's meeting with Beauvoir in Washington, and Lacoste's identification of Margaux Chalifoux expose the conspiracy's connections across organized crime, environmental groups, and the highest levels of government. As the crisis accelerates inside a locked-down Parliament, Gamache must read foreknowledge in a bureaucrat's reaction and trust an enemy's daughter with a dossier that changes everything. The pool closes with Gamache's private confirmation of Woodford's guilt and a quiet final scene that acknowledges the underlying water crisis remains far from resolved.