Two things struck me watching the Oscars. First, pleased though I was that Tilda Swinton won for Best Supporting Actress, whenever I see her now I also hear a chorus of female columnists rushing to champion her ménage à trois with her older partner and younger lover as a shining example of a modern bohemian self-determined lifestyle. Which is all very well, but I cannot help but wonder what these same columnists would have made of a male film star coming out with the same information - I'd very much like to see what reaction, for example, Ralph Fiennes would have got, if, instead of leaving Francesca Annis, he'd announced that he was moving in Jessica Alba. And secondly, I wondered what happened to Good Book, Bad Movie.

This used to be something of a movie producer's credo. And there have been a fair few examples to bear it out: The Beach, Dune, Everything is Illuminated, The Horse Whisperer, The Shipping News, among many. Sometimes, of course, the credo could be reversed, as in The Bridges of Madison County. On the rare occasion when a good film was made from a good book - such as The Witches of Eastwick - it tended to be because the movie bore so little resemblance to the original text.

This awards season, however, has seen a bit of a sea change. Three of the most garlanded films - No Country for Old Men, The Diving Bell and the Butterfly and Atonement - are adaptations, not of pap, but of literary, well-received books. More significantly, perhaps, they are all faithful to the original. Most screenwriting courses teach that the first rule of adaptation is to chuck the novel that has just been optioned into the bin, but Joe Wright, the director of Atonement, has said that the original script for the movie wasn't working precisely because it had forgotten the Ian McEwan story from which it sprung. “So we started again,” Wright stated. “We literally kept the book on one side, and the script on the other, and we slowly worked through it...”

Interestingly, though, it is No Country For Old Men which, as well as winning the biggest awards, remains the most faithful to its literary origins. This perhaps wasn't difficult for the Coen brothers, as the author, Cormac McCarthy, had originally envisaged his tale of blood, drugs and parched Texan landscapes as a screenplay. Reading it, in fact, one wonders how much work Joel and Ethan had to do for their Best Adapted Screenplay gong:

“A darkened room. Smell of rot. He stood until his eyes were accustomed to the dimness. A parlor. A pianola or small organ against the wall. A rocking chair by the window where an old woman lay slumped.”

This, quite clearly, could just be cut and pasted on to the script below the line INT. MOTEL ROOM, JUST AFTER THE SHOOT-OUT.

With his ultra-spare prose and lingering, intense descriptiveness, McCarthy is perhaps a quintessentially cinematic novelist. And yet, watching No Country For Old Men feels rather a literary experience. This is because the Coen brothers stay faithful to McCarthy's tendency to both work within genre and subvert it. The narrative is essentially a western, with shoot-outs and cases of money and chase sequences: but it is also informed by the author's default sense of existential crisis - thus there is no clear divide between good and bad, no easily decipherable character motivations, and, most importantly, no morally resolved ending. All this is in the book, but would normally have been changed in the film. The Coen brothers keep it all: which means that anyone who has seen the film will be aware that when the credits come up after Tommy Lee Jones's final speech recounting an enigmatic dream, everyone in the audience is thinking: “Is that it?”

This is what I mean by a literary experience: you feel challenged, subverted, disturbed and a bit alienated by the movie. You don't cry, or punch the air, or shout “you go, girlfriend” or think “cool” in response to a really big explosion. Thus it's more like reading a post-modern novel than going to the cinema. And thus it has won a lot of awards.

All the above-mentioned films - plus the other biggie, There Will Be Blood - mark themselves out as High Culture. They all deal with the big issues of Life and Death, and they all throw in a bit of self-consciousness about narrative and film-making and the nature of cinematic manipulation. Which is why my favourite film of last year is Juno (also because it's the only one that doesn't have a huge chunk of machismo at its core). It's an incredibly funny and touching screenplay, brilliantly and subtly performed. And it was written for the cinema. The problem with the move towards faithful adaptations of difficult literature is that, in the process, the point of cinema - which I would suggest is different from the point of literature - can get lost.

Meanwhile, if any movie producers are reading, the rights are still available for my new script: Francesca, Jessica and Ralph Too.

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