Montgomery Clift was entering the final months of his life when he shot this film and it's kind of depressing to see how fragile he looks. In medium shots he doesn't look too bad, but when the camera gets in close you can see the gauntness, the way the skin looks parchment-thin across his cheeks. His fingers are orange from nicotine and, even without knowing that he was trying to use this film as an audition for the Brando role in Reflections in a Golden Eye, you can sense a trace of desperation in his eyes. His career was hanging by a thread and he knew it.
The film tells a dour, jaundiced cold war espionage tale in a way that was quite fashionable in its day. It does well in capturing the austere mood of a communist bloc country and the location photography is interesting, but the story is very slow and there really isn't much to it until the final couple of reels. The scene which encapsulates the entire film consists of Clift and Hardy Kruger talking at a table and Clift's contribution to the conversation is mostly to repeatedly ask for his passport. The contrast (and conflict) of their respective countries' ideologies could (and has) make for an interesting subtext for a film, but its treatment is too dour here. There are nice touches, and an expectation on the part of the filmmakers of a degree of attention and intelligence on the part of their audience, but it never really succeeds in its objectives.