In 1951 New York City, Life magazine photography editor Emily Crane is cited by the House of Un-American Activities Committee (HUAC) for refusing to divulge the names of members in her civil liberties group. After losing her job, she responds to a newspaper advertisement for a part-time position reading novels to an elderly Brooklyn woman named Miss Venable. One afternoon, Emily overhears an argument and notices Senator Ray Salwen, the chairman of HUAC, speaking with two German-Jewish refugees who are moving into a neighboring house on adjacent Carroll Street. Although she cannot discern details of the conversation, she notices that Stefan, the younger German boy, acts as an interpreter for the older refugee, Dr. Meyer Teperson. After work, Emily encounters Stefan on the street and they converse amiably about poetry. When she begins to ask questions about his association with Senator Salwen, however, Stefan becomes hostile and runs away. Later, Emily follows him to a cemetery, where he stands over the freshly dug grave of a man named Jesse Sackadorf. Believing he is in danger, she offers to help him, but as she reaches for her business card, Stefan notices a man standing nearby and flees in fear. Back in New York City, Federal Bureau of Investigation (FBI) Agent Mike Cochran and his partner enter Emily’s apartment with a warrant to conduct a routine search. Once they leave, Emily receives a telephone call from Stefan asking for help. They meet at a bookstore, but two government officials arrive and attempt to arrest Stefan. He and Emily weave through the book stacks and disappear in a crowd of theatregoers standing outside. As they sneak backstage, a man emerges from the shadows and stabs Stefan. Police report that Stefan was an undocumented immigrant, but find a list of names in his pocket, one of which is Jesse Sackadorf, the name on the grave. Although Emily encourages them to search the house on Carroll Street, the officers refuse to believe her claims that the boy was somehow involved with Salwen. Sometime later, Miss Venable informs Emily that the neighboring house is no longer occupied. To be certain, Emily throws a rock through the front window and breaks in. Upstairs, Stefan’s killer appears with a knife, but the attack is thwarted by FBI Agent Cochran, who has developed an interest in Emily and continues to follow her. Emily steals one of Stefan’s poetry books inscribed with a falsified signature dated 1851, and believes it is a clue. Cochran and his partner deduce that the name matches that of a ship scheduled to arrive in port the next day. When the boat docks, Cochran and Emily watch as a government official picks up two immigrants and drives away. They follow the men to a wedding reception, where they pretend to be guests. Emily introduces herself to the new arrivals, and recognizes their names from the list found in Stefan’s pocket. Dr. Teperson appears, startling Emily as he tells her—now in perfect English—that she looks familiar. While eavesdropping on another conversation, Emily learns that the immigrants are scheduled to leave on the morning train for Chicago, Illinois. As she sneaks away, a man shoves her into a car and takes her to a restaurant to meet Senator Salwen. Cochran attempts to follow, but a senior FBI officer, who is also attending the wedding, warns the agent that he is outside his jurisdiction. At the restaurant, Salwen reveals that the “Jewish” refugees are actually Nazi war criminals being smuggled into the U.S. to aid the government’s anti-Soviet science programs. He offers to purge Emily’s record in exchange for the names of those who know about the house, but she refuses to talk, and returns home to find Agent Cochran diffusing a bomb he found planted in her kitchen. Unable to cut the wire in time, they run down the fire escape as the bomb explodes, destroying her apartment. Traumatized, Emily bursts into tears. Cochran kisses her, and they spend the night together. Early the next morning, Emily goes to Grand Central Station to follow the departing Germans, while Cochran receives strict orders from his supervisor to abandon the case. Two of Senator Salwen’s men catch Emily snooping around the train, so she escapes through the tunnels. Disobeying his orders, Cochran goes after her as she sneaks into the building and climbs into the rafters high above the main lobby. Senator Salwen follows and grabs her ankle, but Emily kicks free and knocks him onto the plaster mesh ceiling. The material crumbles, and Salwen falls to his death in the station below. Afterward, Cochran boards the train and arrests the “refugees,” exposing Dr. Teperson’s crimes performing experiments on prisoners at Auschwitz. Once the case is closed, Emily resumes work for Miss Venable, and Cochran is transferred to Butte, Montana. He promises to call her, but Emily laments that their relationship was never meant to be.