This semi-realist spy movie about secret agent Quiller (George Segal) trying to find a post-war Nazi base while the Nazis are trying to find the base of the British secret service at work in Berlin suffers from a bizarrely week script by dramatist Harold Pinter where the supposedly highly successful agent Quiller acts like an incompetent tool all of the time. Barely ten minutes into the movie, our supposed hero is falling deeply in love with a highly suspicious school teacher after having known her for about ten seconds (alright, she's played by late 60s Senta Berger, so there is something of an excuse for that).
Quiller walks through the film like a fool, never doing anything that makes him look like a professional, or at least like someone who vaguely knows what he's doing - his plan for finding the Nazis is after all to wander around, ask questions, look suspicious and permanently whine to his superiors for no reason the film ever makes its viewers privy to (usually it's a class thing in British cinema, but this is not a film fond of actually developing anything). Of course, if anyone in the film would not act like a total idiot (don't get me started on the Nazi plan to get Quiller to give them the information they want), Pinter's plot would break down at the first sign of competence.
The wasted actors (there are Alec Guinness playing a higher up in the British secret service hierarchy, and Max von Sydow as the Nazi boss) do their best with their pancake-flat roles, while director Michael Anderson manages to improve things with a lot of excellently moody shots of the non-tourist parts of Berlin. If you're able to not think about the script's basic lack of believability (I'm sure somebody is going to tell me Pinter meant the whole thing metaphorical and just ignored that he also needed to construct a world and characters an audience can believe in because that would have disturbed his precious metaphorical level), there are also some rather tense suspense scenes late in the film that would have been even more excellent if their basic set-ups (again) would not ask for ignoring a bit too much of their logical weakness.
These plot holes (I can't believe this film makes me of all people complain about plot holes) would not be much of a problem if the film itself wouldn't go for a semi-realist mood. Silly nonsense works well enough in a Eurospy film that wants to be pulpy fun and out-Bond Bondian silliness, but if you're going for a mood that's much less larger than life, you need to keep that mood consistently, something Anderson and Pinter fail to achieve.