This gritty adaptation of John le Carré's gruelling novel finally offered Richard Burton a role worthy of his wonderfully world-weary style, after years wasted on sullen romantics. Bitterness seeps from every pore as he goes behind the Iron Curtain for a final showdown with his East German counterpart. With agents trapped behind state secrecy and false identities, this isn't the glitzy neverland of James Bond, but a dangerous reality in which suppressed emotion matters more than derring-do. Martin Ritt's icy direction and Oswald Morris's bleak black-and-white photography make this not just the most authentic Cold War film, but also one of the best.

British agent Alec Leamas refuses to come in from the Cold War during the 1960s, choosing to face another mission, which may prove to be his final one.