Nurse Nellie Forbush (Mitzi Gaynor) of the U.S. Navy falls for middle-aged French plantation owner Emile De Becque (Rossano Brazzi), but recoils upon discovering that he's fathered two mixed-race children. When Nellie leaves him, the heartbroken Emile agrees to take on a dangerous espionage mission. In his absence, Nellie struggles to reconcile her prejudices with her love for him -- and after she spends time with his children and comes to care for them, fears that Emile may not return alive.