As war flares in North Africa, the U.S. consulate in Tangiers is flooded with Americans desperate to return home. Among them is Brenda Ballard, who has obtained a forged passport in exchange for her services on behalf of German espionage. Brenda meets Barry Corvall, an attache at the consulate, when she staggers into his office and faints. Barry, who is returning to Washington to attend foreign service school, becomes infatuated by Brenda, and when the two sail for America on the same boat, he falls in love with her. Although Barry proposes night after night, Brenda refuses to marry him because she knows that he comes from a family of career diplomats and her past would destroy his future. In Washington, Barry completes his studies, and upon passing his examinations, he is assigned to the Paris consulate. Against his mother's wishes, Barry finally becomes engaged to Brenda, and on the eve of their marriage, Karl Muller, a German spy, appears and orders Brenda to steal some secret plans. Compelled by Muller's demands, Brenda confesses her past to Barry, thus forcing him to resign from the foreign service. Realizing that the U.S. has no defense against spies like Muller, Barry determines to expose the workings of the espionage ring. He and Brenda decide to risk their lives by going to Geneva to infiltrate the ring. There, Brenda convinces Paul Strawn, one of the spies, that she and Barry are willing to sell U.S. military and industrial secrets. Discovering the location of the spies's headquarters, Barry eavesdrops on a meeting and learns of their plans to spread national disaster throughout America. Realizing that he needs evidence to convince Congress, Barry and Brenda try to flush the spies out of their headquarters with the plans. Their scheme backfires, however, and Rader, the head of the ring, takes Brenda hostage aboard a train bound for Germany. Barry follows and rescues Brenda, and after securing the plans, they make a daring escape by plane. In Washington, Barry uses his evidence to convince the government of the necessity to combat espionage in the U.S.