Washington, D.C. socialite Connie Mathers flits from party to party and earns a living wearing clothes from chic dress stores as a form of advertising. One afternoon, she is enjoying herself at a party when her sister Agatha's boyfriend, military intelligence agent Elliott Salmon, announces that the United States has entered World War II after the attack on Pearl Harbor. The revelers are horrified and begin discussing how they can help the war effort. Connie is humiliated when Thomas Aldrich, the wastrel son of a wealthy and influential ship manufacturer, states that they both will be of no use to their country because of their lack of practical skills and experience. After stating that she could become an effective spy, Connie leaves the party and returns to her apartment, where she is confronted by a mysterious man who calls himself Mr. Fortune. Fortune, who is an Axis agent, tells Connie that he works for the U.S. Secret Service, and needs her help to catch an informant who is leaking naval secrets to the enemy. Connie is uncertain whether to believe him as he cautions her not to reveal his visit to Elliott, and states that her instructions will come in the form of dress shop bills that can be decoded with the use of the book Gone With the Wind . Later, Fortune sends her a test message ordering her to wait at a certain location, but when Connie goes there, she is left waiting in the rain for half an hour. While she is waiting, Tommy drives by, and Connie assumes that the whole thing has been a practical joke concocted by him and she ignores further messages sent by Fortune. After another agent warns her to follow instructions, the flighty Connie confides her dilemma to Elliott. During their luncheon, however, Elliott receives a telephone call and subsequently disappears. Connie is terrified and agrees to cooperate when Fortune assigns her to find out if Tommy is the informant. As Connie spends time with Tommy, they fall in love, although Connie's affection for him is tempered by her fear that he is an Axis agent. She is also worried about her sister Agatha, who is kidnapped shortly after coming to visit her. Although Connie insists that Tommy is innocent, Fortune orders her to try to bribe him to steal his father's conference notes, which contain valuable information. When Connie offers Tommy a large sum of money to show her the notes, he does so, believing that she is merely joking. Fortune appears at the Aldrich house as Connie is typing up the notes and kidnaps her and Tommy. The couple are taken to an abandoned mill on the Hudson River, and Connie finally realizes that she has been duped. She and Tommy manage to free themselves from their bonds, and as they struggle with their captors, Elliott and Agatha, who are also being held there, free themselves as well. Elliott uses Fortune's shortwave radio to send a phony message to Fortune's Japanese allies so that they will be picked up by U.S. forces. Connie then reflects on how she sunk a Japanese submarine and won Tommy in the same adventure.