A really good spy film, unlike the stupid cliches of 'James Bond' and 'Mission Impossible' series, is about mind games. It's about struggling against mind-fields to discover a truth hidden in plain sight, and decoding it.
In such a really good spy film, no clue is spoon fed to the audience with tricks like slow motion, highlighted comments or scenes or by focusing on a character to either prove then guilty, or mislead viewers. A true spy film, like the profession of espionage itself, is about teasing the viewers, making them squirm in their seats with discomfort.
A really good spy film is like 'Tinker Tailor Soldier Spy' (TTSS).
In the height of the cold-war of the 1970s, there's a rumour of a double agent in the top echelons of British Secret Service. After an agent walks right into an ambush in communist Budapest, the suspicions gather wind. A retired agent, Smiley (Gary Oldman) who has intricate knowledge of his own and other agencies, is recalled. He realises that the clues to the mystery lies both in the present and a party a few years back, that keeps playing in his mind.
In a good 'find the mole, plug the hole' spy film, the needle of suspicion keeps circulating and does not spare even the investigators. 'Trust no one, till the end' is the motto, thus confusing, and challenging the viewer.
In a good spy film, the clues are never given en-masse. Instead they are scattered like dust specs in the air, visible only when light is shone on them. They are all over, hidden amidst many other incidents that can also equally be clues. Finding answers thus become like building a jigsaw puzzle, only in this case there are as many useless pieces that do not belong in the jigsaw, as there are those that do.
A good audience is the one, that picks the right one, is able to make the connections and find the mole before the protagonist does. And if you pay attention in the film, you will. But blink and chances are that you will miss it.
That's because the film overlaps past and present as clues are thrown in plain sight. Yet, like time bombs they tick along in your subconscious till just at the right time they explode in your conscious mind and you realize you knew it all along.
Having said that TTSS, with its complex plot and not so easy way of delivering clues, is a film meant only for select, intellectually vigorous viewers who miss no clue, no little suggestions, who can 'tinker' clues to 'tailor' together the most implausible meanings with a 'soldier's' spirit and a 'spy's' enthusiasm. You can test the limits of your ability to comprehend the most inane of clues with this film.
Giving credence to its sinister and broody mood of mistrust is an excellent cast that delivers a spectacular performance. Gary Oldman is cold, calculative just as his character requires while John Hurt, in a small but significant role is his usual, animated self.
The film has issues, like the reason given by the mole to do what s/he does. That, however, does not matter because if you got the film, you'll rejoice and if you didn't it will end up being one of the most harrowing films you have ever seen. John le Carre, on whose 1974 masterful spy novel the film is based, would be very proud indeed.