It took 290 minutes over seven parts for the BBC to adapt John le Carre's chilling novel of betrayal and intrigue for television in 1979. That this big-screen version occupies less than half the time is a credit to co-writers Bridget O'Connor (who died of cancer a week before shooting started) and Peter Straughan, whose screenplay is a masterpiece of concision and precision: not a word or a glance is wasted and there's none of the flabby expository dialogue that makes the TV series sound quite clunky now. Whole chains of events are disposed of in a sentence. Yet only as the loose ends are tidied in the last couple of minutes is there a sense that things are hurried and indistinct.
This approach is more than just practical: it adds to the creeping sense of tension because we're constantly off-balance, plied with just enough information to keep up. The film is far from hard to follow, but it punishes the least lapse in attention.
It's an unlikely thriller: there's no car chase or fistfight and the few shots that are fired are widely spaced. Most of the time, men talk in offices or dark city streets - the palette is all cool blues and drab browns and scarcely a ray of sunlight pierces the gloom.
And it's absolutely riveting from start to finish.
More than 20 years after the Berlin Wall fell, a story based in Cold War paranoia might seem dated. But director Alfredson, the Swedish wunderkind behind the macabre vampire romance Let the Right One In, knows that it's more than a story of its time and place.
Morally complicated and positively dripping with disenchantment and existential angst, it's a timeless revenge tragedy, a story of secrets, lies and the struggle for power.
The plot is simple enough: spymaster George Smiley (Oldman, whose change of eyewear in the first reel is a calculated bow to the most famous Smiley, Sir Alec Guinness) is pensioned off along with his boss (Hurt) after an abortive operation behind the Iron Curtain. But Whitehall mandarins prevail on him to come out of retirement to investigate intelligence that a Soviet agent is working in the upper echelons of MI6 (known as "The Circus").
Working in flashback - and, crucially, returning to several scenes including an important office party to re-examine them from different characters' viewpoints, Alfredson has assembled a Chinese puzzle of a film in which a fantastic cast, working mainly in medium close-up have everything written on (or concealed by) their faces.
In a clever touch, each floor of the service's building seems to take on the character of the man who presides there, so we have a sense of moving across dangerous borders: a set piece in which a document is smuggled out of the archives is a nailbiter.
And Oldman's Smiley is a triumph, a textured and complex character, no less hard to read than Guinness', but quite without the late master's self-effacement. There's a viperish intelligence behind those owlish eyes and this film packs a hell of a punch.
Cast: Gary Oldman, John Hurt, Colin Firth, Toby Jones, Ciaran Hinds, Benedict Cumberbatch
Director: Tomas Alfredson
Running time: 127 mins
Rating: M (violence, offensive language)