This is one of Alfred Hitchcock's most suspenseful thrillers.
Cary Grant stars as a US government agent who gatecrashes a party held by the daughter (Ingrid Bergman) of a wartime traitor.
Through the use of charm, and a little blackmail, he persuades her to go to Brazil in order to get close to an ex-Nazi (Claude Rains) who is plotting against the United States.
The assignment is full of danger, and the hotter things get for her, the more concerned and romantically fascinated Grant becomes.