The Madness of July by James Naughtie, book review: Tale of treason in high places

James Naughtie is the ultimate Westminster insider. If you need to disappear a dead American from a cupboard in the House of Commons, he's your man. Lock "the door at the top of the stairs" and back up your van to "where the passage gives on to Speaker's Court". The American turns out to be a spy, but there is more than spy fiction here: murder, family drama and political thriller.

Will Flemyng, a former spook turned Foreign Office minister, maintains that spies "came in two guises: the silk-smoothies who were always quiet and listening, or the unbuttoned wide boys". Flemyng, the most self-effacing spy hero ever, clearly belongs to the former. The book itself is tight lipped; the reader has to piece together a drip-feed of clues – and the process becomes addictive. The first clue is the book cover. A midnight rower sculls past the Palace of Westminster, but as you turn the book over, the river is no longer the Thames. Find that river and you're on the trail.

Naughtie (left) never talks down. You're expected to know that the Cabinet Secretary isn't someone taking shorthand, but the UK's most powerful civil servant. Likewise, a passing reference to a "dingy tower block" signals that a character works out of Century House, the 1970s HQ of MI6. Naughtie is not so sure-footed with things American. US passports at the time were green, not "dark blue". And his attempt at New Yorkais, "World Series, my ass! For-ged-about-it'" is as authentic as Dick van Dyke's Cockney.

Set in July 1976, the hottest summer in British history, political tensions come to a boil. These tensions, however, are fictional. Other than the heat wave itself, The Madness of July is devoid of historical fact or innuendo. Harold Wilson's resignation, our biggest unsolved political mystery, took place four months before. But that elephant is not in the room. Nor is there a single character with the slightest resemblance to any figure of the time. On the other hand, Naughtie has woven together a tale of treason in high places that is very probable – and may refer to a past far more recent than the 1970s. Back to the book cover; the real traitors weren't working for Moscow.