Charlie Kaufman, the writer who bent reality into knotty shapes in Being John Malkovich and Adaptation, has done it again. This time, his chosen genre is the biopic, rendered between slices of documentary testimonial from people who worked with the subject of the film, the American gameshow pioneer Chuck Barris. At least, they look like people who worked with him. They could be actors. But Barris is real, and this story is based on his autobiographical journals (though he is played by Sam Rockwell). This doesn▓t make it true, as there exists the strong possibility that Barris was a) making it up, or b) nuts.

The action starts with Barris, naked, in a New York hotel room as, on television, that other showbiz faker Ronald Reagan is sworn into office. Barris is reflecting glumly on his wasted life. "When you▓re young, your potential is infinite ..." Time passes, the realisation sets in: "You weren▓t Einstein. You weren▓t anything. It▓s a bad moment."

The action flips back to Barris▓s seedy childhood - he only wanted to be loved - then to the start of his television career. This section resembles the uniformed nostalgia of that other autobiographical crime caper, Catch Me if You Can, and is an unconvincing opening. There is something a little too plastic about the vintage television cameras, the men in bow-ties, the girls drinking Coca-Cola through straws. For a while, it looks as if Clooney the director is going to wing it on charm, the way Clooney the actor did in Ocean▓s Eleven. There is something a little too loving about those scenes of men in candy-striped blazers, downing tumblers of whisky on antique jet planes. Happily, while Spielberg was nostalgic and soft-hearted, Kaufman and Clooney are misanthropic. The unreality of the television world is heightened to emphasise its emptiness, and to underscore Barris▓s contention that his success was hollow.

That success - writing a hit record for the Palisades, inventing The Dating Game, The Newlywed Game and The Gong Show - gives Barris access to everything he wanted, notably girls, who line up for loveless sex. He meets Penny (Drew Barrymore), the love of his loveless life, while he is standing naked inside a refrigerator, and she fumbles inside the door, looking for beer.

So far, so showbiz. The story lurches left with the appearance of CIA special agent Jim Byrd (Clooney, in trilby and moustache, looking like a cross between Clark Gable and Donald Sutherland). Byrd invites Barris to undertake some "problem-solving" work of a diplomatic nature: code for becoming a freelance assassin. "Call it patriotism."

Is it plausible that the CIA would hire a gameshow host as a hitman? Well, in Barris▓s world, where everything is implausible, it seems as likely as anything, and the spy scenes are shot in light that emphasises coldness and grit. The actual hokum of espionage, though, is as playful as Bond: see the scene where Barris accompanies Bachelor No 3 to a wintry Helsinki and encounters his contact, Patricia (Julia Roberts): a fantasy spy in black hat, black fur and white kinky boots. He attempts to chat her up by quoting Nabokov: "All the information I have about myself is from forged documents."