5 Fingers (1952) review

Ulysses Diello (James Mason), an Albanian-born valet who works for the British ambassador to Turkey, offers to sell top secret documents to German attaché Ludwig Carl Moyzisch (Oskar Karlweis) during World War II, which the Nazis reluctantly agree to (but are understandably skeptical) - Diello partners with financially impoverished Countess Anna Staviska (Danielle Darrieux) to hide the thousands of British pounds, except she's not remotely trustworthy.  What's intriguing about this wartime story is not only that it's (loosely) based on true events (after the war, the real Moyzisch documented his experiences) but almost all of the principal characters in this are utter scoundrels, and it isn't until English intelligence officer Colin Travers (Michael Rennie) appears - as a generic symbol of Morality - that there's anyone who can stop the "bad" people.  Mankiewicz's approach may be a bit icy but this cloak and dagger stuff is rather nasty business ... although the last shot, of Diello realizing he's been outsmarted and Anna is ruined, is memorable.