Somewhere at the very highest levels of British Intelligence there stands a double agent, a "mole," implanted deep in its fabric, perhaps decades ago, by Moscow Centre. He can only be one of five men—brilliant, complicated men, proven in action, who have worked closely together through the years, respecting and depending on each other, despite the central imperative of their profession to trust no one.

Of these five, it is George Smiley, perhaps the most brilliant and complicated of them all, who is tapped to dig out the mole and destroy him. And so Smiley embarks on his blind night walk, retracing path after path into his own past––its aliases, covers, sleights of hand––burrowing into the dust of unresolved episodes.