As part of a special documentary television program, elderly Linda Voss hesitantly agrees to be interviewed and recounts her experience as an amateur spy during World War II. The child of an Irish mother and German-Jewish father, Linda kept her heritage a secret while growing up in Queens, New York, after learning of her cousins’ struggles to survive in Nazi-occupied Germany. In 1940, Linda applies for a secretarial position in the office of international lawyer Ed Leland, who hires her because she is fluent in German. Before long, Linda learns her stoic and mysterious boss keeps close contact with U.S. President Franklin D. Roosevelt and FBI (Federal Bureau of Investigation) Director J. Edgar Hoover, and frequently disappears for weeks at a time. Realizing the letters she translates are written in code, she becomes increasingly suspicious that he is a spy. By October of 1941, Linda and Ed have grown attracted to each other and begin a secret affair. Following the bombing of Pearl Harbor, the U.S. enters the war and Ed is forced to expose his true identity as a U.S. Army colonel working for the OSS (Office of Strategic Services) in Washington, D.C. When Ed is called away to Europe, Linda gets a job in the War Department and deciphers a message revealing that Ed has long since disappeared behind enemy lines. Six months into the war, she is shocked to see Ed arrive at a USO (United Services Organization) party with an attractive female officer. Although he suggested they end their relationship before his departure, Linda has come to realize how much she loves him, and he grudgingly rehires her. When an undercover U.S. agent is murdered in Berlin, Linda eagerly volunteers to replace him. Citing her love of espionage films and familiarity with the mission’s codenames, she offers to pose as cook in the home of Nazi officer Horst Drescher to collect evidence of Germany’s “flying bomb.” Ed vehemently opposes the idea, claiming Linda is too outspoken to withhold secrets, but eventually yields to her insistence. He agrees to send her to Berlin with top U.S.-German operative Konrad Friedrichs, codenamed “Sunflower,” on condition she promises to return to Switzerland in exactly two weeks’ time. Worried about her lack of experience and lower-class German accent, Sunflower recruits his niece, Allied agent Margrete Von Eberstein, to refine her skills. The women become fast friends, and Margrete introduces Linda to her Nazi mother, Olga Leiner, as a former schoolmate. On the night of an important dinner party, Linda is brought in as a last-minute replacement for Drescher’s cook, bypassing usual security checks. The meal is a disaster, however, and Drescher fires Linda for embarrassing him in front of his honored guest, Franze-Otto Dietrich. After the party, Dietrich offers Linda a job as a nanny and she accepts, after noticing confidential documents stuffed in the officer’s briefcase. Over the next five weeks, Linda cuts off all communication with Ed and reaches out to her contact in Berlin, a fishmonger, who informs her that her father’s Jewish relatives are hiding on the outskirts of the city. Meanwhile, Ed traces her location and rushes to Berlin with an immediate escape plan. Determined to save her family first, she negotiates permission to stay an additional twenty-four hours. In the morning, Linda brings Dietrich’s two children to her cousins’ address, but is heartbroken to discover they have recently been captured. When Linda and the children are caught in the destruction of an air raid, Dietrich’s son reveals the existence of his family’s secret bomb cellar. Instead of meeting Ed at the train station, Linda stays at the Dietrich house and uses a microfilm camera to photograph the documents hidden downstairs. Accompanying Dietrich to the opera the following night, she is recognized by Olga Leiner, who believes her to be one of Margrete’s school friends. Her cover now blown, Linda seeks refuge with Sunflower, but the old man orders her to go to Margrete’s house instead. Once there, she discovers Margrete is a Nazi double agent who betrayed the location of her cousins. Margrete shoots Linda, but Linda wrests the gun from her grasp and kills her. She evades the Gestapo by hiding inside the laundry chute, and eventually passes out from the pain of her injuries. In the morning, Ed and Sunflower search the house and follow a trail of blood into the basement. Disguised as a Nazi officer, Ed carries her body to the train station, where they board a train bound for Switzerland. As they leave the city, Ed declares his love for Linda and expresses regret for having “let her go.” At the Swiss border, he pretends to be mute to hide the fact he does not speak German. When the Nazi officers notice Linda’s papers are out of date, Ed kills several guards and attempts to escape with Linda on foot. Although shot twice in the leg and back, he stumbles over the borderline and collapses safely onto Swiss soil. In the hospital, doctors find a roll of microfilm stuffed inside Linda’s glove, which contains the photographs of Dietrich’s documents. As Linda concludes her story, she introduces the interviewer to her two sons and invites Ed to sit with her on camera.