In the tension-filled backdrop of 1989 Berlin, just before the infamous fall of the Berlin Wall, MI6 agent James Gasciogne (Sam Hargrave) meets a tragic fate at the hands of KGB operative Yuri Bakhtin. Bakhtin not only murders Gasciogne but also steals a vital piece of intel known as the List — a microfilm hidden within a wristwatch, containing the identities of every active field agent in the Soviet Union. This crucial document was originally provided to Gasciogne by an informant code-named Spyglass, who had been promised immunity by MI6. With the potential to prolong the Cold War for four more decades, governments scramble to obtain it, and Bakhtin remains a persistent threat in Berlin.
Just ten days after the shocking assassination, top MI6 spy Lorraine Broughton (Charlize Theron) is summoned for a debrief by MI6 executive Eric Gray (Toby Jones) and CIA operative Emmett Kurzfeld (John Goodman), to discuss her sensitive mission to Berlin, which unfolds in a series of gripping flashbacks.
The very next day after Gasciogne's death, Lorraine is deployed to recover the List and to eliminate Satchel, a treacherous double agent who has been feeding sensitive information to the Soviets for years and is implicated in Gasciogne's betrayal. The list may hold the key to Satchel's true identity, which explains MI6's intense interest in it.
Meanwhile, Spyglass reaches out to David Percival, the MI6's head operative in Berlin, to inform him that he had passed the list to Gasciogne. However, Percival refuses to acknowledge Spyglass due to Gasciogne's absence and insists that he still lacks the list. Undeterred, Spyglass claims he has committed it to memory.
Upon her arrival in Berlin, Lorraine is quickly ambushed by KGB agents affiliated with arms dealer and KGB ally Aleksander Bremovych (Roland Møller), yet she manages to escape thanks to the timely intervention of her primary contact, David Percival (James McAvoy). Percival claims he has never met Spyglass, but the risks escalate as Bremovych is also hunting for Bakhtin, intent on acquiring the List.
As she searches for leads, Lorraine combs through Gasciogne's apartment where she stumbles upon a photograph of him and Percival, leading her to question Percival's loyalty. Additionally, Lorraine forms a bond with naïve French agent Delphine Lasalle ([Sofia Boutella]), who has been tailing her since she set foot in Berlin.
As the plot thickens, Bakhtin reveals his plan to auction the List to the highest bidder. Percival, having learned this intelligence, acts first by killing Bakhtin and taking the List for himself, later meeting with Bremovych while Lasalle captures the incriminating exchange on camera.
Percival contacts Lorraine with news that Spyglass, the officer who memorized the List, wishes to defect. Lorraine, feeling frustrated by Percival's delay in informing her, jumps into action. That night, Percival betrays both Spyglass and Lorraine during an extraction attempt, resulting in the tragic death of Spyglass, confirming Lorraine's worst suspicions about Percival's treachery.
In a stirring turn of events, it becomes evident that Lasalle had been following Lorraine with Percival's knowledge. When Lasalle confronts Percival about his dealings with Bremovych, he brutally murders her to silence her. Lorraine arrives too late to save Lasalle but uncovers hard evidence of Percival's betrayal.
As Percival attempts to escape after setting fire to his hideout, Lorraine confronts him, leading to a fierce confrontation where she retrieves the List. In a shocking revelation, it appears that Percival's true objective was to eliminate Lorraine as she is, in fact, the real Satchel, a bold player in this perilous game of espionage.
Upon returning to MI6 for a debriefing, Lorraine skillfully presents the incriminating evidence against Percival, concealing the whereabouts of the List, which forces MI6 to drop the case. In a breathtaking climax, she later meets with Bremovych in Paris, revealing her true identity as Satchel. She hands over a fake List, yet Bremovych is not fooled, acknowledging her cunning.
Before she finally deals with his henchmen, she discloses that she has been orchestrating the events from the outset. Shortly thereafter, in another twist, she meets with Kurzfeld, disclosing that she is actually a CIA triple agent before returning to Langley, leaving a trail of deception in her wake.
