In the present (1992), elderly Linda Voss (Melanie Griffith) is interviewed by a BBC documentary team about her experiences before and during World War II. She explains that, growing up in New York City as a young woman of Irish/German Jewish parentage, she always dreamed of visiting Berlin and finding her family members there. In 1940, Linda applies for a job as a secretary with a major law firm, but is rejected because she did not graduate from a prestigious women's college. As she leaves, however, Linda impresses the supervisor by demonstrating that she speaks fluent German, and she is hired as a translator for Ed Leland (Michael Douglas), a humorless attorney. She soon becomes suspicious of his strange behavior and mysterious whereabouts, and begins to suspect that he is actually a spy, and they eventually become lovers. After the attack on Pearl Harbor, when America joins the war with the Allies, Ed emerges as a colonel in the OSS. Linda accompanies him to Washington D.C., but he is suddenly posted away, leaving her alone and devastated. Assigned to work in the War Department, she hears nothing of Ed until one evening in a night club, when he reappears with an attractive female officer. Reluctant to resume their affair, he does re-employ her. Ed and his colleagues need to replace a murdered agent in Berlin on very short notice. Despite knowing little about intelligence work, Linda volunteers and Ed is persuaded by her fluent German and passion to contribute to the war effort. Her mission is to bring back data on the V-1 flying bomb.
Ed and Linda travel to Switzerland, where he hands her over to master spy Konrad Friedrichs (John Gielgud), who takes her by train across the border into Germany, to Berlin, where he hides her in his house and introduces her to his niece, Margrete von Eberstein (Joely Richardson), a socialite also working as an Allied agent. Linda assumes the identity of Lina Albrecht, and is planted as a cook in the household of Horst Drescher, a social-climbing Nazi officer, before an important party he is throwing, but she arrives too late to prepare the food properly, causing the dinner to be a disaster, and Drescher angrily fires her. Walking dejectedly on the dark street, alone, after curfew, Linda chances to encounter a guest from the dinner, officer Franze-Otto Dietrich (Liam Neeson), who is charmed by her and mistakenly assumes she must already have had a security check. Dietrich is a widower and takes Linda/"Lina" on as a nanny to his two children. Between her duties as a servant, she searches Dietrich's house for confidential papers on the V1, which he is also working on. She intends to photograph them, but can find nothing. Meanwhile, Ed, sick with worry about Linda since her disappearance from Drescher's party, suddenly chances to see her in a newsreel of Hitler in a parade in Berlin. Ed's agents identify Dietrich as the man standing next to Linda in the film, and Ed heads to Germany to rescue her. Because he does not speak German, he assumes the identity of a wounded high-ranking German officer, who has had his throat injured and cannot speak. He tracks down Linda and tells her she must leave with him immediately, but Linda reveals that she has located her Jewish cousins, excitedly telling Ed and Margrete how nearby they are. She demands Ed give her another day to visit them and give them hope. The next day, with the children in her care, Linda tracks down her relatives' hiding place in the city, but she finds it empty and ransacked, they have just been captured. When an allied air raid suddenly hits, Linda has to run for cover with the children and protect them, and when they get back to the house, the frightened boy inadvertently reveals the existence of a hidden room in Dietrich's basement. Linda sneaks down there that night and finds and surreptitiously photographs Dietrich's top secret V-1 rocket blueprints. Dietrich has fallen in love with Linda, and invites her to the opera. While there, Linda's cover is blown when Margrete's mother recognizes her, believing Linda to be a friend of her daughter's from college. Dietrich is heartbroken and, once back at his house, Linda sees him loading his gun.
Fearing for her life, Linda flees across the city, still in her ballgown, and finds sanctuary with Margrete. When Margrete thinks Linda is not looking, she uses the phone to report in to her superiors, but Linda catches her. Margrete reveals that she is a double agent, who betrayed the agent Linda replaced, causing his death, and that she gave away the location of Linda's Jewish cousins to the Gestapo. Margrete shoots Linda, wounding her, but they struggle and Linda overpowers Margrete and kills her. Linda hides in the laundry chute, escaping the German forces who raid Margrete's apartment. Badly wounded, Linda is found by Ed and Friedrichs, who take her to the railway station. Ed and Linda travel to the Swiss-German border. Linda is unconscious from blood loss, barely alive, and Ed's travel papers have expired. Ed's mute act fails to sway the border guards, forcing him to shoot his way out. Carrying Linda, he struggles towards the border. The German sniper guarding it shoots and wounds him twice, but he gets himself and Linda across before collapsing. Back in the present, Linda reveals that while she and Ed recovered from their injuries in a Swiss hospital, the microfilm of the secret German documents was retrieved from a hiding place inside her glove, and the Allies successfully bombed the V1 installation. Ed then walks out to join the interview, and they reveal they have been happily married ever since.
Michael Douglas as Ed Leland
Melanie Griffith as Linda Voss
Liam Neeson as General Franze-Otto Dietrich
Joely Richardson as Margrete von Eberstein
John Gielgud as Konrad Friedrichs a.k.a. Sunflower
Francis Guinan as Andrew Berringer
Anthony Walters as Dietrich's son
Victoria Shalet as Dietrich's daughter
Sheila Allen as Olga Leiner, Margrete's mother
Stanley Beard as Linda's father
Sylvia Syms as Linda's mother
Ronald Nitschke [de] as Horst Drescher
Hansi Jochmann as Hedda Drescher
Mathieu Carrière as Capt. Von Haefler
William Hope as Major Kernohan
Constanze Engelbrecht as Stafson Von Neest
Ludwig Haas as Adolf Hitler
Wolf Kahler as German Border Commandant
based on the novel of the same name by Susan Isaacs