John Fitzgerald Kennedy to Marilyn Monroe. The date is November 1993. Oswald's bullet was a little off and someone found Marilyn while there was still time for a date with the stomach pump. This is alternate-history courtesy of journalist and erstwhile Late Show presenter Mark Lawson in his debut novel, Idlewild. Everything is subject to change.

The airfield at Idlewild, of course, became JFK after the man's death. Only now that hasn't changed and the ageing President muses on how he'd like to become an airport. Everything else has however - Teddy Kennedy died bravely trying to save a young woman at Chappaquiddick while Pres-brother sparks catastrophe in South East Asia. Oliver Stone knows the score: he's preparing LBJ for next season. Marilyn won't be in that though. The blimping sixty-seven-year-old is busy making her comeback, appropriately, in She's Back! as a star returning from the dead, and watching herself on too much insomniac late-night TV. It's what surviving does to you.

But there are always the fruitcakes. One of them is the latest in a long-line of literature's loon-Presidents, a man called Sanders, an independent with a self-confessed non-interest in politics, and an obsession with reincarnation, master of home-bake philosophy: "Back home, we say, good news and fat women, it's the but you have to look out for."

Another is the "English assassin" Meredith, with high-power connections to men whose names begin and end in vowels. And who is this Fraser - The Time Bandit - a man equally determined to make sure the thirtieth anniversary of Dallas should not go unremarked? And why does he obsess so on the texts of Stephen Hawking and intricacies of the Multiverse? "Fraser briefly contemplates shooting Hawking, for writing books that make the ordinary Joe feel slow and small."

And the conspiracy theorists all gather at a Dallas hotel for a symposium of sad. Was Kennedy really an Off-Broadway actor after Dallas? Who was murdered at Chappaquiddick? What secrets do the number-crunched digits 112263 really mask? And what riddles lurk inside the Who Shot JR? episode of Dallas, broadcast on the eve of the 18th. anniversary of the shooting? (Frighteningly, Lawson didn't even have to make this stuff up.)

Idlewild is a book about situations and icons rather than character or emotion. Lawson claims the idea came from covering the 1988 Presidential race and the way Dukakis tried to style himself on the Kennedy legend, a tactic so successful for Clinton later on. (Not in these pages, mind you.) Certainly, he does America really well, loading up on detail and ripping through his text in pedal to the metal (70 chapter) sound-bites.

The comedy (yes, it's very funny) is broad, but well-judged and distinctly black: child abuse, and the brilliantly targeted bad taste assassination-attempt sweep aside all those of faint heart. It's too long - lose the last thirty pages - so it whimpers on after the bang that should call it in, and occasionally it is just a little too clever for its own good, but such are minor gripes. This is a superior entertainment.