The espionage thriller Black Bag (2025) begins on a deceptively quiet evening in London. British intelligence officer George Woodhouse (Michael Fassbender) meets secretly with his superior, Meacham (Gustaf Skarsgård), who reveals a devastating breach: Severus, a top-secret government program, has been compromised. Even more alarming, one of the five top suspects is George’s own wife, Kathryn St. James (Cate Blanchett). Meacham gives George one week to uncover the traitor.

A Suspicious Dinner Party

To start his internal investigation, George and Kathryn host a private dinner at their home. They invite the remaining four suspects—each a close colleague: surveillance expert Clarissa Dubose (Marisa Abela), her boyfriend and operative Freddie Smalls (Tom Burke), agency shrink Zoe Vaughn (Naomie Harris), and high-ranking officer Colonel Jimmy Stokes (Regé-Jean Page).

Secretly drugging the food with a mild sedative, George tries to shake loose secrets under the guise of a casual game. Tensions escalate quickly. When George initiates a “New Year’s resolution” game, Clarissa fires a sharp accusation at Freddie, calling out his infidelity—then stabs his hand. Freddie barely reacts, dulled by the sedative. Suspicion simmers beneath the polite surface.

George’s Private Pursuit

Digging deeper, George finds a stub for a movie titled Dark Windows in his bathroom. When he casually brings it up, Kathryn pretends she’s never heard of it—igniting George’s paranoia. Soon after, Meacham dies suddenly, seemingly from a heart attack. George doesn’t buy it and covertly plants Meacham’s work badge in Kathryn’s belongings. He later uses it to enter her office, uncovering a surprise: a secret solo trip to Zurich.

As Kathryn meets Zoe for a therapy session and discusses her turbulent relationship with George, she subtly probes Zoe about her affair with Colonel Stokes—turning the tables in her own investigation.

Meanwhile, Colonel Stokes meets George during a fishing trip and drops a bombshell: someone is using the alias “Margaret Langford” and hiding £7 million in a covert Zurich account.

Layers of Lies

George convinces Clarissa to pivot a spy satellite to surveil Kathryn in Switzerland. Through the feed, he spots her meeting with a Russian contact, deepening his suspicions. At the same time, Zoe tries to distance herself from her relationship with Stokes, but he warns her that she still holds dangerous intel from their past—especially about Severus.

Stieglitz (Pierce Brosnan), Kathryn’s boss, convenes a private meeting with George, Freddie, and Stokes. He claims a Russian agent named Pavilchuk has escaped with Severus, potentially triggering a nuclear catastrophe. Stieglitz hints that someone inside the agency enabled the breach—implying George is to blame for ordering the satellite redirect.

Freddie, feeling betrayed, tells Kathryn about George’s suspicions. George and Kathryn finally confront one another. Realizing someone else may be pulling strings, they team up to uncover the true mole.

Closing in on the Real Threat

Kathryn and Clarissa analyze the satellite data, tracking the Russians’ movements. Their new theory? Stieglitz is the true mastermind. They suspect he leaked Severus to collapse world governments and profit from the fallout. A drone strike is launched using their intel, wiping out the Russian operatives.

To confirm their suspicions, George organizes polygraph tests for Zoe, Stokes, Freddie, and Clarissa. All are asked the same question: when did you first learn of Severus? George and Kathryn compare answers and find just enough inconsistency to justify a final confrontation.

Truth and Consequences

George and Kathryn host another dinner—this time with a loaded pistol placed prominently on the table. As the night unfolds, George lays out everyone’s secrets: Freddie and Zoe’s affair, Zoe’s early knowledge of Severus, and most damning of all—proof that Colonel Stokes and Stieglitz colluded to leak the software, knowing it would cause mass casualties.

In a last-ditch effort to silence George, Stokes grabs the pistol and confesses. He poisoned Meacham and worked alongside Stieglitz to unleash Severus. But the gun holds blanks. Calmly, George pulls out a second weapon and kills Stokes.

Kathryn warns the remaining guests: if anyone dares to manipulate her or George again, they won’t get a second chance. The couple dumps Stokes’s body—together.

Final Resolution

In the closing scenes, Kathryn confronts Stieglitz and tells him he’s lost. Severus has failed. Back home, she and George reflect on their survival and reconnected trust.

But one unresolved thread remains: the £7 million still sitting in Zurich.