Hitchcock’s Notorious. Ingrid Bergman hired to spy on former Nazis in Rio largely on the grounds of her notable promiscuity, with nuclear age intrigue so current for 1945 that the FBI had Hitchcock under surveillance. Tense stuff once the plot gets rolling, and a great unraveling ending.
Also worth watching for its top-notch use of rear projection special effects: if you think that modern movies and tv shows use a surprising amount of green screen for inserting fake backgrounds, it’s worth remembering that it’s an old idea. All of the foreground action for Notorious was filmed on set in California, with background footage shot by a 2nd production crew in Rio and Miami, beautifully worked in behind the actors so that it’s really hard to tell sometimes.