Friends Bill Morley and Rosey Blake both spy debutante Penelope Craig at an American Red Cross blood drive and are attracted. Bill, a playboy flyer, pretends to be a doctor in order to meet Penny and get her address and phone number for his "little black book." That night, Bill and Rosey crash Penny's parents' anniversary party at the Craigs' home, and to get even, Penny exposes Bill's deception by introducing him to some old family friends: hypochondriac Mrs. Cartwright and physician Dr. Crane. Before he leaves her parents' home, however, Bill kisses Penny, and she immediately falls in love with him. Penny then follows Bill to a Burbank nightclub, which is near the Vega Aircraft factory where Bill and Rosey work on the assembly lines. Later, Penny and Bill go to the beach, and Bill tells her that she should not get involved with him, as he is not the domestic type and is merely waiting for his papers to join the Air Force. Not to be dissuaded, Penny gets a job at the aircraft factory, and when she is unable to find Bill in the giant plant, she performs a song at lunch to attract his attention. That night, while the Craigs are screening home movies, Bill comes over to their house and tells Penny that he has gotten his orders. They try to break up, but quickly discover that they have fallen in love and decide to spend what little time he has left in the United States together. Just before Bill is about to leave for overseas duty, however, Hannah Gordon, one of Penny's friends at the factory, learns that her flyer husband has been shot down over the Pacific. Penny then goes to her father Judson and asks him to use his influence to keep Bill at the aircraft factory. Judson refuses and tells Penny that it is her duty to support Bill's induction into the military. Penny then returns to the factory to learn that Bill has decided to end their relationship. Later, Bill tells Rosey that he ended his romance with Penny to spare her the pain he saw Hannah suffer. Rosey then goes to the Craig home and tries to give Penny a note, telling her that Bill really loves her, but Judson has ordered Binns, the family butler, not to allow either Bill or Rosey in the house. Penny receives the note, however, and races to the airport in time to say goodbye to Bill. When he tells her that he is still worried about her, Penny, paraphrasing Hannah, replies that "if he flies 'em, then she'll build 'em."