William Powell, Rosalind Russell, and Cesar Romero star in this espionage thriller with romantic comedy touches, based on a book by the real-life head of the U.S. Secret Service during World War I. Before shipping out, new Lieutenant Bill Gordon (William Powell) becomes attracted to Joel Carter (Rosalind Russell) who, upon learning that Bill used to be a newspaper puzzle editor, arranges for him to be transferred to the War Department, where he is put to work breaking codes for Major Brennan (Lionel Atwill). When Brennan is murdered as the result of a German-Russian spy ring's machinations, Bill investigates the spies and a comely secret agent (Bonnie Barnes), which jeopardizes his newfound romance with Joel.