Le Carré's recent novels have portrayed, with a great deal of detail and diligently evoked atmosphere, two distinct worlds of espionage: Smiley's world in London, a domain of desks and files and intrigues and research, an awkward corner in the corridors of Anglo-American power; and the world of the active agent, the field….

In "Smiley's People," Smiley works both worlds, is both detective and agent at risk. I won't disclose the oblique, slow-moving plot, except to say that a trail of murder and camouflage leads Smiley to Hamburg and Paris and Berne, and that the stakes are especially high for him, since his old archenemy … appears to have made an uncharacteristic slip….

There is a lot of nostalgia among le Carré's spies. They hark back to World War II, or even the cold war, when people at least thought they knew who their enemies were. But...