The match for the world chess championship held in Reykjavik, 1972, was not just a contest between individuals but a clash of ideologies. In the red corner: defending champion Boris Spassky, backed up by a team of grandmasters and KGB agents, bolstered by all the resources of the Soviet state apparatus. In the blue corner: 29-year-old Brooklyn boy Bobby Fischer, lover of hamburgers and ping-pong, champion of democracy. With the world's media watching, it was Rocky versus Ivan Drago, with the same inevitable flag-waving victory for freedom.

At least, that's how the story usually goes. David Edmonds and John Eidinow, and their impressive team of researchers, have combed Soviet records and American intelligence files, and interviewed nearly every surviving actor in the drama, to give a more nuanced account of a match that was characterised by extreme mutual paranoia. Far from being an obedient Soviet puppet, for example, the brilliant Spassky was a semi-dissident playboy. His own recollections about his chess-playing career in the USSR, how victory afforded his family a "palatial" two-room apartment but defeat meant he was banned from playing abroad for two years, constitute some of the best parts of the book.

The one interviewee notably absent, however, is Fischer himself. The standard biography is repeated: the early childhood in New York chess clubs, winning the US championship at 14, missing out on one world championship cycle through a fit of pique, and then finally bulldozing his way to the match against Spassky by crushing three of the top players in the world.

Fischer's run of 20 straight victories against top opposition at that time still stands as an unparalleled display of dominance. He is one of three or four reasonable candidates for the title of greatest chess player who ever lived.

Yet after beating Spassky in Reykjavik, he refused to defend his title in 1975 and became a notorious recluse. He now lives in Japan, occasionally granting interviews to Icelandic radio in which he expounds his theories of global Jewish conspiracies. (In an appendix, Edmonds and Eidinow claim to have discovered the identity of Fischer's biological father: if they are right, then both Fischer's parents were Jewish, which casts his vitriolic anti-semitism in an even more tortured light.)

This is all very familiar, compared with the fresh and valuable testimony of Spassky and other grandmasters and officials. Mysteriously, the authors do not even relate whether they sought an interview with Fischer. The consequent problem is that the story's most intriguing character is seen only second-hand, flattened rather than rounded out by the piling up of clichИs about his "volatile genius".

More than any other game, chess seems to invite amateur psychoanalysis. Vladimir Nabokov, in the preface to his chess novel The Luzhin Defence, refers sarcastically to "the curative insinuation that a chess player sees Mom in his Queen and Pop in his opponent's King". And Fischer has invited such comment more than most, much of it uncritically reproduced by the present authors. They relay, for example, the following ludicrous notion: "Grandmaster Reuben Fine, a psychoanalyst, thought Fischer's ambiguous feelings towards women could be read off from moves like Nh5."

Sadly, Edmonds and Eidinow are themselves eager hack psychologists. As a boy, Fischer would demand another game if he lost at speed chess. To the authors, this perfectly normal behaviour "hinted at a deep psychic need to reconstruct his self-image - that of a winner". Elsewhere we are told, in wondering tones, that "the only objects Fischer appeared to feel an emotional affinity for were his chess pieces" (I would be interested to see the authors' list of Objects Approved for Emotional Affinity, perhaps including teddy bears, bicycles and model spaceships). And then there is stuff such as "Chess players can often feel insecure in open, complex positions because a part of them dreads the unknown", in which the weaselly tautological "can often" might even be read as a subconscious acknowledgment that the authors are talking rubbish. Perhaps worst of all, they wield the word "psychopath" insinuatingly, without ever quite coming out and accusing their subject of being one.

The best retort to this unfortunate strain of the book comes in Fischer's own words: "I don't believe in psychology. I believe in good moves." The authors quote this without perhaps realising quite how much of their own text it torpedoes. For it takes a grandmaster of literary style - a Nabokov, a Stefan Zweig or an Ezra Pound, say - to write well about chess in a non-technical way. The present authors are not so gifted, and their desultory shorthand descriptions of the chess games ("as is common in the GrЭnfeld, [Fischer] sniped away at white's centre"; "Spassky's two bishops grandly commandeered the board, gaining between them a sweeping control of the long diagonals") are likely to leave non-players utterly baffled, and players frustrated.