There's an authenticity about the performance from Richard Burton in this cold war thriller that, alongside some well paced direction from Martin Ritt really helps it hit home. His character ("Leamas") is assigned one final task, to deal with the duplicitous Peter van Eyck ("Mundt") who appears to be systematically removing the West's reliable sources of information. What follows is a far more psychological cat-and-mouse game as he gets apprehended, and has to play a very dangerous game balancing the needs of his mission with his own survival instincts - all of this without much clue as to whom he can really trust and against a backdrop of thinly veiled prejudices. John le Carré's books were always packed with detail - and that detail carries well into this film, it offers a richness to the proceedings that ensures we are drawn into the plot like a mouse after the cheese. Claire Bloom adds a diversion to the intensity - but in a sophisticated fashion - maybe she's just innocent, or could she actually be involved? Oskar Werner, Robert Hardy, Michael Hordern and a rather menacing Beatrix Lehmann all play important cogs in the wheel too. It's a watch that requires a degree of concentration - like the story itself, blink and you might miss something... important!