Passport to Treason (1956)
Boy is this an obvious attempt to be something that it can't quite be. That is, it's a low budget off-beat British movie with an American main character acting like a tough film noir detective. The London fog is thick, the femme fatale (in a nightclub) is cool and mysterious, the police are bothered but mostly clueless, and a crew of Italians are interfering with some kind of anti-peace movement. It even starts with a voice-over, at night, with a laconic world weariness that Bogart made so famous in a couple of his early detective thrillers for Warner Bros.
"Passport to Treason" is moody and not terrible, but if you like all the usual touch points of an American detective noir, you'd be better of with the real deal, of which there are so many better ones, even low budget ones like this. But for now, here we are, and the dark drama is enough to keep things going much of the time. Of course, it would help to have a compelling main character, and the large, deep voiced detective is played by a bit of a bore, Rod Cameron. He has the voice and pace of Lon Chaney Jr. without the sympathetic aura. Of course, since he's American he can take out three well prepared Italian thugs in a warehouse without any trouble, and he can solve the crime even the police don't quite know how to get at.
The main trick is that Cameron's character has stepped into another detective's shoes. So it starts with a deception. Then the Italians try some kind of mind control, coming out of the brainwashing scares of the Korean War I suppose. And at first he works for one client, then another, never quite getting paid for all his back and forth. And behind it all is an international underground group working for world peace. That's right. It's a noble but slightly abstract idea, maybe more tangible in Europe in the 50s than here, then or now, in the U.S. But it's hard to get involved. Eventually things resolve, and that's that.
Honestly, what is really interesting here is just the way a film noir cliché translates into a British realm. The cars and accents are different, but so is a certain feel to the actors and their style. Don't expect much.