The only thing missing in his life was chess. His MI5 minder suggested he join the Central London Chess Club, a venerable institution founded by a group of civil servants during the First World War. His application form was a master-piece of ambiguity. It supplied no address, no home telephone, no mobile, and no e-mail. His occupation was described as “translation services,” his employer as “self.” Asked to list any hobbies or outside interests, he had written “chess.”

But no high-profile case is ever entirely free of controversy-and the old hands warned they had never met a defector, especially a Russian defector, who didn’t lose a wheel from time to time. Grigori’s came off the day the British prime minister announced a major terrorist plot had been disrupted. It seemed al-Qaeda had planned to simultaneously shoot down several jet-liners using Russian-made antiaircraft missiles-missiles they had acquired from Grigori’s former patron, Ivan Kharkov. Within twenty-four hours, Grigori was seated before the cameras of the BBC, claiming he had played a major role in the affair. In the days and weeks that followed, he would remain a fixture on television, in Britain and elsewhere. His celebrity status now cemented, he began to move in Russian émigré circles and cavort with Russian dissidents of every stripe. Seduced by the sudden attention, he used his newfound fame as a platform to make wild accusations against his old service and against the Russian president, whom he characterized as a Hitler in the making. When the Kremlin responded with uncomfortable noises about Russians plotting a coup on British soil, Grigori’s minder suggested he tone things down. So, too, did his editor, who wanted to save something for the book.

Grudgingly, the defector lowered his profile, but only by a little. Rather than pick fights with the Kremlin, he focused his considerable energy on his forthcoming book and on his chess. That winter he entered the annual club tournament and moved effortlessly through his bracket-like a Russian tank through the streets of Prague, grumbled one of his victims. In the semifinals, he defeated the defending champion without breaking a sweat. Victory in the finals appeared inevitable.