When you're in one of the hippest bands on Planet Earth, and your first album has received the kind of obsequious reviews that make the reception given to Pet Sounds look positively lukewarm, what do you do for your next gambit?

A concept album encompassing the death of Tutankhamun and the battle of the Little Big Horn might be an option, as might a decision to spend the next two years smoking crack in an appendix-shaped swimming pool out the back garden (indeed, (a) might follow (b) in short order).

If you're Air, however, you will get commissioned to record a downbeat, abstruse suite of electro-symphonic sketches for the soundtrack of a movie about teen suicide. It's not the most straightforward career move in the world, but then, as anyone who heard Moon Safari and last year's singles compilation Premiers Symptomes will attest, Air's name has become a byword for the unobvious way of doing things.

Jean-Benoit Dunckel, known as "JB" to his friends, is one half of the finest musical unit to emerge from France since Little Bob Storey (anybody remember "Riot In Toulouse"? No? Oh, okay). He and songwriting partner Nicolas Godin first came to prominence in early 1998 with the release of Moon Safari, acclaimed by all and sundry as one of the finest debut records of the last decade.

A serenely beautiful collection of mostly instrumental serenades processed through space-age technology, it was followed swiftly by the aforementioned singles compilation. More adulatory reviews ensued.

And now, sitting in an office somewhere in southern Paris, at the other end of a crackly phoneline, JB talks in halting but largely impeccable English about the largely exquisite 40 minutes of music they created for the Virgin Suicides soundtrack late last year.

The film is the directorial debut of Francis Ford Coppola's daughter, Sofia, who was last seen prancing around in a gymnast's costume in the video for the Chemical Brothers' Elektrobank, and who had hitherto been best known for making a disgrace of herself in The Godfather Part III, where she hammed it up artlessly in the role of Michael Corleone's daughter.

Given that she is married to Spike Jonze, the man responsible for more eye-popping video clips than Hype Williams (and usually with around a tenth of the budget), it would be surprising if she hadn't picked up a few visual-sleight tricks from her other half. And indeed, advance reports suggest that The Virgin Suicides is a genuinely handsome-looking film, full of muted shades of blue and green, replete with leisurely panning shots and super-slow-motion closeups across inordinately lavish sets and backgrounds.

Whether it's any good as a piece of cinema remains to be seen. The source material sounds promising: it's adapted from Jeffrey Eugenides' 1994 novel about five beautiful sisters from a wealthy New England family who each kill themselves in turn.

The Virgin Suicides (the book) is dark, powerful stuff, and often gratuitously morbid. It's full of little details like how most people who commit suicide by jumping from a height are later found to have torn muscles in their arms from grasping at thin air as they fall, such is the strength of the survival instinct. Shortly before his disappearance, Richey Edwards of the Manic Street Preachers nominated it as his favourite book of 1994. Captain Corelli's Mandolin it ain't.

"The overall mood of The Virgin Suicides, the movie, is very impressive," observes JB. "It's all about the fascination with love and suicide, sex and death, and with our music we were trying to capture that."

Air's latest effort, almost by default, has joined the relatively puny canon of soundtracks - and here I'm referring to original scores, rather than merely collections of songs featured in the movie - which stand up to the test of being heard anywhere outside the cinema or confines of the video recorder.

The 40-minute suite has some genuinely lovely moments, including the dark, trippy synthesiser-waft of Bathroom Girl, the beautifully serene Dirty Trip, and the Pink Floyd-inspired psychedelia of Clouds Up. The only thing on it resembling a proper song is the opening track and recent single - Playground Love, a stately, strings-drenched piece of Moog organ-driven elegance.

Sensibly, JB regards most modern soundtracks with disdain, viewing them as cheap cash-in jobs with often only the flimsiest of connections to the original flick. "I don't like when they have this thing of, you know, Music From And Inspired By The Motion Picture". It's just a way for them to put anything they want on the soundtrack. Then you are left with a mutant record. It's not good.

"Perhaps my favourite soundtrack is A Clockwork Orange," he continues. "It has some beautiful music in it, some strange sounds. I have always liked it. Another one is Le Mepuis. That's a Jean-Luc Godard film from 1965. In it there's a 40-year-old man who has an accident, and he falls in love with a young girl, played by Brigitte Bardot, who is a virgin. What happens is a very strange love affair, and the film deals with that, about the emotion and intensity involved. The two of them become swallowed by each other, and Le Mepuis is all about that . . . all about the dark way of loving."

He tends to talk like this a lot.

"As regards soundtracks," he continues, "we are big fans of Bernard Herrmann. But we think of him in very academic terms. By that, I mean we look up to him a lot, we want to learn new ways of doing things from him. It's like he is the master and we are pupils. In soundtracks, as in life, we are attracted to strange things! Ha ha ha ha!""

Is JB worried that this soundtrack will be viewed in some quarters as the bona fide follow-up to Moon Safari?

"It's obvious that it is not," he replies. "Most of the people who listen to our music are aware of what we get up to. Doing this (The Virgin Suicides) was very good preparation for the new album. We have done seven tracks so far and we have three more to go. It will be out at the start of next year at the latest."

In terms of its overall mood and sound, what shape is the record currently taking?

"It's more mad, more extreme than Moon Safari. On the contrary to what I was saying earlier, the tracks will be longer. There is one song that lasts for eight minutes and is in three sections. But that's the way we work - we just turn up (at the converted chateau 10km outside Versailles where they record) with one idea in our heads, and we do it. Sometimes it takes as little as four hours. On the other hand, Sexy Boy took a whole year."

Does he envisage the record taking them to a higher commercial plateau than its predecessor, in view of the extra publicity now gained from this foray into the world of cinema?

"Perhaps," he muses. "In one way we regret that Moon Safari did very well, because of all the promotion we must do now. You have to sell yourself, sometimes it's aggressive, and we don't like that.

"Ideally we wouldn't do promotion at all. Perhaps we will get to the state of not having to sell our record because we are big (laughs). Artists have three things to do in their lives - recording, playing live, and promotion. And we only like the first of those things, and the second sometimes. But the most important thing is to have something to say, and to communicate it. And that's why I'm talking to you now."

The Virgin Suicides is out now on Source/Virgin France.