Charlie Chan is an agent of the US government working in Washington DC and he is assigned to investigate the murder of the inventor of a highly advanced torpedo. Aiding Chan is his overeager but dull-witted son Tommy and his daughter Iris.

Roger Hudson, a wealthy businessman who has moved to Washington to work for the government as a "dollar a year man," is late for a radio broadcast about his new department, the Mobilization of Woman Power for War. He takes a cab driven by Dixie Dugan, who hopes that being a cabbie while the country's men are away fighting will help the war effort. Her incompetent driving, however, results in an accident for which Roger must take responsibility in order to reach the radio station in time. Dixie then returns home, where she lives with her father Timothy, who is constantly practicing his air raid warden duties, her mother Gladys, an aspiring Red Cross worker, and cousin Imogene, who studies incessantly to become a "quiz kid." The Dugans rent out their spare rooms to Dixie's fiancé, Matt Hogan, and to blustering Judge J. J. Lawson. Matt, who works in a munitions factory, wants Dixie to settle down and marry him, but Dixie is determined to help her country.

Larry Haines, a mediocre vaudeville entertainer, boards a train for Los Angeles. Aboard, he meets an attractive, blonde British agent carrying a coded message hidden in a brooch—and is being pursued by Nazi agents.

经历一连串失败的恋情后，这对密友达成协议，决定冒险再次寻觅真爱 — 但他们也许就是彼此的真爱呢？