Disturbing plothole
I found the most essential part of the plot being flawed:
The purpose of the whole intricate plot by the Brits was to free Mundt from suspicion of being a double agent, in which they succeeded - but however that SHOULD NOT have framed Fiedler "guilty" in any sense...Fiedler was acting perfectly logically with his accusation of Mundt... which shouldn't/couldn't be counted against him. So there's a slight logical flaw there.
In other words when they "proved" that Mundt was not guilty, they same time proved that Fiedler had been played by British intelligence...against his knowing.
However I enjoyed the intricate plot and great acting so I'm still giving this a 9/10, the film kept me in it's grip from start to finish and made me even thinking about the ending afterwards, figuring what actually happened in the end.