After World War II, Hitler's deadliest lieutenant escaped.
On Christmas Eve in 1944, SS-Obersturmbannführer Adolf Eichmann (Kingsley) flees the Eastern Front to Berlin to coordinate the destruction of documents related to Department B4, going into hiding after the war ends.
In Buenos Aires, Sylvia Hermann (Haley Lu Richardson) begins courting Klaus Eichmann (Joe Alwyn). Klaus meets Sylvia and her German-Jewish father, Lothar (Peter Strauss) at home. Klaus speaks of his father’s service with the SS but tells Lothar that he had died on the Eastern Front, and that he has been raised by his uncle, Ricardo. Suspicious, Lothar passes this information to West German prosecutor-general Fritz Bauer. Bauer, suspecting Klaus’ uncle may in fact be Adolf Eichmann, relays this intelligence to Mossad director Isser Harel (Lior Raz) in Tel Aviv, but Harel is unwilling to devote resources to investigate. At the insistence of Rafi Eitan (Nick Kroll), Harel dispatches field agent Zvi Aharoni (Michael Aronov) to Buenos Aires to begin reconnaissance. At a dinner party celebrating Argentina’s 150th anniversary of independence from Spain, Klaus introduces Sylvia to Carlos Fuldner, a former Nazi officer who assisted with SS members escape to Argentina. Fuldner addresses the guests with anti-Semitic rhetoric invoking the Hitlergrüsse, leaving Sylvia visibly disturbed, who promptly leaves.
Working in coordination with Mossad, Sylvia meets the Eichmann family at their home on Garibaldi Street to apologize for her earlier actions, and after an uncomfortable exchange between Klaus and his father, who introduced himself to Sylvia as Herr Klement, departs. Eichmann is subsequently photographed by Aharoni’s assistant and intelligence of the exchange between Sylvia and the Eichmann family is relayed back to Israel, including information on how Klaus referred to Eichmann as “Father”. Eitan summons Mossad agent Peter Malkin (Oscar Isaac) and briefs him on the operation to capture Eichmann and to bring him to Israel, to stand trial for war crimes. Unconvinced of his ability to gather intelligence on his own, Eitan and Harel chastise Malkin for a botched capture that resulted in the death of another Nazi in Austria in 1954 that they believed to be Eichmann. Malkin persuades Harel the operation would be successful if Eichmann were captured and extracted by airplane on board an El Al flight, under the cover of a diplomatic mission during the Argentinian anniversary. Harel agrees to proceed with the operation after medical doctor Hanna (Mélanie Laurent) is convinced to join the team. After briefing on intelligence collected by Aharoni, Harel dispatches the team to Buenos Aires, who arrive on 1 May 1960.
The capture team, composed of both Mossad and Shin Bet agents, begin surveillance, with Malkin determining Eichmann to be a creature of habit. Harel approves the capture on 7 May, with the team to capture Eichmann while on his way home from work. The team executes the plan on 11 May, with Malkin capturing Eichmann outside his home, and subsequently extracted to a Mossad safe house. In the scuffle, Eichmann loses his glasses. Klaus investigates the commotion after the capture team flees and finds his father’s glasses. When approached by Carlos on who knew Eichmann’s true identity, Klaus realizes Sylvia or her father may have been involved. As Eichmann’s identity is confirmed at the safe house, the Israeli embassy is notified that Lothar Hermann was arrested and the police subsequently identify him as Josef Mengele. Meanwhile, the capture team is informed by the transport plane’s company (El-Al) that they will only transport Eichman if he is to sign that he will voluntarily travel to Israel to stand trial. Knowing Hermann’s arrest was a ruse to encourage Eichmann’s release, Harel orders Aharoni get Eichmann to sign the document to depart Argentina voluntarily. Eichmann, who refuses to interact with Aharoni, also refuses to sign the waiver. In contrast, Eichmann attempts to bond with Malkin during his watch and is able to further persuade Eichmann to sign the agreement requested.
As Klaus and Carlos investigate further, they recover a sketch Eichmann drew of Aharoni’s assistant who photographed him, which is relayed to the local police for additional assistance. Pressure grows against the capture team with the airline departure days away, and authorities now searching the nearby neighborhoods for Eichmann. With time running out, and despite Aharoni’s disapproval of Malkin’s methods, including disclosing his own name to his prisoner and providing comforts, he is successful in breaking Eichmann, who subsequently signs the waiver. At the same time, a Nazi sympathizer working at the safe house provides information on the capture team to the police, and Carlos has Graciela brutally beaten to reveal where Eichmann is being held. Disturbed at her treatment, Klaus is able to persuade Graciela into providing information on his father’s location. As the safe house is scrubbed and Eichmann is loaded, Eitan volunteers to stay behind due to a lack of room in the car for the trip to the airport. Klaus arrives at the safe house too late, and they make way for the airport. At a security checkpoint, a security guard recognizes Aharoni’s assistant from a copy of the sketch and notifies the police. The flight is subsequently delayed due to an issue with the flight permit. With Carlos, Klaus and local police en route to stop the flight, Malkin rushes to air traffic control with their flight permit in hand, to ensure the plane takes off without issue. Malkin subsequently remains behind and catches a separate flight home, while the capture team tearfully embraces and congratulates each other on the operation.
In the closing scenes of the film, Israeli Prime Minister David Ben-Gurion announces over radio that Adolf Eichmann has been captured and will stand trial in Israel. Eichmann is visited by his wife Vera while in prison, and Klaus flies the flag of Nazi Germany over their home in protest. Footage of various Nazi war crimes is played during the opening statements by the prosecution. As Malkin leaves the trial, Eitan remarks they will not be remembered through recorded history for who they were, only for what they accomplished. The closing credits recap the outcome of the trial itself, overlaid with live footage and images of testimony from Holocaust survivors. On 1 June, 1962, Adolf Eichmann was executed by hanging, having been found guilty of transporting millions of people to their deaths. He was cremated in an oven built for the occasion, and his ashes spread in the Mediterranean Sea, so that he might have no final place of rest. The trial was televised globally. It was the first time that eyewitness testimony of the Holocaust was seen by the world. Malkin kept the mission secret from his mother until she lay on her deathbed, and Malkin himself died in 2005, survived by his wife and three children.