Diplomatic Courier is a 1952 American spy film noir directed by Henry Hathaway and starring Tyrone Power, Patricia Neal and Stephen McNally.

In post-WWII Europe, Mike Kells returns to Paris from a courier mission, only to be immediately re-assigned by the State Department to fly to Salzburg and meet his Navy friend Sam Carew, who will pass a top-secret document to him on a particular train platform.

After he leaves, it is Joan who is revealed to be the Russian agent when she meets with Rasumny Platov to discuss the strategy on getting the top secret papers, details of an invasion plan, back into Soviet hands.

He retrieves the watch from the pawn shop where Janine left it, only to have Joan try to take it from him at gunpoint before she is surprised and overpowered by the faithful American Sergeant.

Mike is captured by the Soviets, drugged, his clothes and possessions searched, and when nothing is found, he is dumped in a river, from which he is rescued by a passing fishing boat.

Janine bargains with the Soviet agent Platov for her freedom by agreeing to give the microfilm to them; in return they will accompany her on a train to the border of the security zone.

Casey Robinson and Liam O'Brien...have assembled an impressive array of melodramatic occurrences, such as a mysterious murder on a train, muggings in Trieste, double dealings and, of course, a climactic "chase"...But they haven't concocted a story that has clarity or suspense, and Mr. Hathaway has not been able to direct it so that it looks like anything on the screen";[6] whereas Time Out called it a "Neat, taut espionage thriller".