The year is 1997, where we find Rachel Singer (Helen Mirren) being celebrated by her daughter, Sarah (Romi Aboulafia), at a book release event in Tel Aviv. The book recounts the harrowing account of events that took place in 1965 involving Rachel, Stefan (Tom Wilkinson), and David (Ciarán Hinds). As the festivities unfold, David is taken by an Israeli government agent for a debriefing, momentarily reconnecting with Stefan, whom he recognizes in a waiting vehicle. Unable to cope with the weight of their shared deception, David tragically takes his own life by stepping into the path of an oncoming truck.
The narrative then shifts back to 1965, where we meet a young Rachel Singer ([Jessica Chastain]) embarking on her first mission as a Mossad agent in East Berlin. Her task is to collaborate with seasoned agents, David Peretz (Sam Worthington) and Stefan Gold (Marton Csokas), to apprehend the notorious Nazi war criminal, Dieter Vogel (Jesper Christensen), infamously known as "The Surgeon of Birkenau". He is feared for his heinous medical experiments on Jews during World War II. In their covert operation, Rachel and David pose as a married couple from Argentina, while she infiltrates Vogel's clinic as a patient seeking fertility treatments.
As the mission progresses, Stefan shares with Rachel the anguish of David, who lost his entire family during the Holocaust, driving his commitment to the mission while simultaneously causing David to hesitate in forming deeper ties with Rachel. There’s undeniable chemistry between them, but Rachel finds herself entangled with Stefan after a moment of vulnerability where David turns her down. Their intimate encounter leads to Rachel becoming pregnant, adding another layer of complexity to their already dangerous mission.
During Rachel's final doctor’s appointment, she seizes the opportunity to inject Vogel with a sedative and creates a medical emergency that allows Stefan and David to extract him. Disguised as paramedics, they narrowly escape with Vogel from the clutches of impending capture. The trio's attempt to exfiltrate him at the Wollankstrasse Station turns chaotic when Vogel awakens, triggering an alarm. In a desperate act of heroism, David sacrifices his safety for Rachel, leading them to reconsider their escape strategy and ultimately bringing Vogel back to their hideout.
Bound by the walls of their apartment, they take turns monitoring Vogel, who attempts to break their spirits through psychological torment. David eventually snaps during a confrontation, channeling his past traumas into a violent reaction against Vogel. However, when Vogel manages to overpower Rachel, she is left with a permanent scar, symbolizing both her physical and emotional struggles. After a tense moment, and under panic regarding their deceit, the trio concocts a narrative that Vogel was killed in the escape attempt.
Years pass, and the agents are celebrated as heroes for their efforts. However, during a dinner at Rachel and Stefan's home in 1970, the facade begins to crumble. Rachel confides in David, expressing her discontent with her life under Stefan's controlling nature, which drives a wedge between her true feelings for David. Eventually, David resolves to leave, asking Rachel to join him. Torn between her responsibilities and desires, they part ways.
At a subsequent dinner following Sarah's book release, Stefan reveals new information regarding Vogel, who he learns is now in a mental asylum in Ukraine. Haunted by the past, David reflects on the lives they've irrevocably impacted due to their deception, ultimately leading to his tragic end.
Entrusted with a new directive from Mossad, Rachel feels compelled to retrieve the truth. She travels to Kiev and begins her search for Vogel, conducting her investigation and breaking free from the confines of their carefully crafted lie. Upon reaching the asylum just prior to a journalist’s arrival, she discovers that the man claiming to be Vogel is merely an impostor. With a newfound determination, she vows to no longer continue the deception.
However, fate takes a turn when she uncovers the real Vogel, leading to a dramatic confrontation where she ultimately claims victory, ensuring justice is served. As she exits the asylum, a note detailing the truth of their original mission is left behind, ready to spill the secrets that had been buried for decades. Through her harrowing journey, Rachel seeks to reconcile her past and reveal the reality of their choices that shaped their lives and the lives of many others caught in the shadows of history.
