Chris Cleave, the London novelist taking the world by storm

London's literary scene, says 35-year-old best-selling novelist Chris Cleave, is "absolutely rocking at the moment". "London is unbelievable," he says excitedly. "You couldn't invent it. There are 300 languages, 72 major nationalities and, despite what people would have you believe, it's largely self-policing because we all actually get on with each other.

"It's become this place where it doesn't matter what you look like, where you're not defined by your ethnicity, and it's exotic and exciting and fun, and that doesn't happen anywhere else on earth - except perhaps New York, certainly not Paris - and that, to me, is civilisation " He pauses briefly for breath. Cleave's London-ophilia is torrential: "I go to these book events, to parties, and I meet these brilliant writers, and whatever their ethnicity, the fact is they live in this place where anything is possible and where the imagination can have free rein. It's so exciting. London is where literature really is at right now."

We're sitting - with a certain bathos given this panegyric - in Cleave's poky garden shed at the bottom of his modest south London garden. This is where he works every day on a laptop, away from the distractions of a very young family (Louis, five, and Joe, two); and where, each week, he receives by email the steadily growing sales figures for his second and latest novel, The Other Hand. It's also where he received the "rather amazing" news that Nicole Kidman, no less, wants the film rights to it.

The Other Hand is one of those rare books that catches the publishing industry off-guard - a novel that barely shifts in hardback but in paperback, without advertising or much marketing, suddenly begins to sell through word-of-mouth, and within months becomes a cast-iron hit. In the past eight weeks, it has sold 100,000 copies; has garnered six film offers; and next month is featured as the inaugural novel on a new nationwide breakfast book club broadcast by CBS in America. This latter, you suspect, will send sales in the US soaring.

"It's all been very surprising," he says, with a small, delighted grin. "I mean, I'm genuinely surprised that so many people have taken to my stuff like this."

The Other Hand is very much a London novel, and deals precisely with the cultural mix that Cleave so celebrates. Its principal characters - a dissatisfied, adulterous magazine editor and a 16-year-old Nigerian asylum seeker - apparently share nothing but a single experience of horrific violence, yet eventually, temporarily, form the kind of "family" that could perhaps exist only in London. Much of the action takes place in the city's classically middle-class districts such as Kingston upon Thames and occasionally stretches belief in its rather chattering-class idealisation of migrant innocence. But Cleave, who interviewed former internees of Britain's 10 immigration removal centres for the book, has constructed a cleverly compelling plot - and a series of scenes that stick in the mind for sheer horror.

Cleave's novel-writing career was itself a form of migration - from a solid future in business to a much less secure life in fiction. Indeed, he grew up an economic migrant, in Cameroon, where his father moved the family for work. "My father was a super-qualified chemist but couldn't find employment here during the 1970s recession, so went out to Africa to build a Guinness brewery.

"I was eight when I came back to a pretty tough state school in Hillingdon, and I didn't fit in for quite a while. I didn't get playground culture. I didn't get cold weather. I didn't get Britain."

He was bright enough to get into Oxford, however, and, after university, went to work for the late Nineties internet phenomenon lastminute.com. At that point it was a thriving business and Cleave loved it. "But I also wanted desperately to write. I had an epiphany quite late on, when I was 19 and read Primo Levi for the first time. It was then I realised how powerful literature can be." Unable to resist, he cashed in his valuable lastminute shares, and moved to Paris with his French wife - giving himself two years to write a book. He was published within 18 months.

Appropriately, that first novel, Incendiary, was a baptism of fire. It took as its bloody subject the aftermath of a fictional terrorist attack at an Arsenal-Chelsea match, and was written in the form of an open letter to Osama bin Laden, a conceit that caused huge controversy four years after 9/11. In the months preceding publication the book was advertised in Underground stations, reviewed widely, and condemned for tastelessness in more than one newspaper (including this one). Cleave, nervous about the book's reception ("It could have been construed as anti-Islamic; it's not, but it could have been "), felt overwhelmed. Yet there was a terrible twist still to come: Incendiary was officially published on 7 July 2005.

What did he think when he switched on the TV and saw the bombings on the morning of his novel's launch? "I thought I'd lost my mind," he replies. "It was extremely spooky." And then he says something startling: "It affected me in an absolutely concrete way, because I thought it was my fault "

But how? "You have to remember the context: there was a huge ad campaign and it was well known in London that this controversial book was coming out. I didn't think it was impossible that the next phone call I'd get, someone would say: these bombings are a response to your book, and deliberately carried out on the day it's supposed to be published. Stranger things have happened. Look at the whole Salman Rushdie affair.

"Now, at a distance of almost four years, that seems like hubris. I'm just a minor writer doing my thing - it was nothing to do with me. But at the time I genuinely thought I was to blame." Cleave has never told this story in such detail before. He's an intense but affable sort of bloke, and you can tell even the memory is uncomfortable. "I was actually very scared. For about three days, I don't mind saying I couldn't hold it together. One of the things I did was move my family to a safe place. I got really paranoid, and didn't sleep for at least a week."

Later, he met many of the survivors of 7/7 at the launch for a book that told their stories. "In a way I was in awe of those people. They were in wheelchairs, on crutches, with bits of their jaw missing, and all milling around this little bookshop in Kew not talking about it. They were talking about Wimbledon and the weather. It was so incredibly British."

Still, thanks to his early childhood in Africa, Cleave doesn't feel particularly British himself, not in a "patriotic way". He does, however, feel like a Londoner. "It's my place. I have this loyalty to London because it's earned it, you know?" He grins; we are back on his favourite subject. London's literary scene, he concludes, is moving beyond the trend for novels that describe the city from a purely ethnic point of view - books like Brick Lane and White Teeth - and towards a London novel that blends and merges the experience of all.

"I think Monica Ali and Zadie Smith are great but there was a rash of novels like theirs about five years ago, and I got so pissed off. We should be past the point at which people think your story is interesting just because you're ethnic. Your story should be interesting because you've got something to say - and that applies to characters in a novel as much as to writers. Look at a writer like Alex Wheetle, stereotyped as a black British novelist from south London, who is actually just mesmerisingly brilliant "

He is warming up again. "In fact, I do think that readers are generally pushed a bunch of books that are very much like the ones they've just read. It's the industry's fault. There should be fewer books published and they should be much bloody better "

But what is it about London beyond its racial mix that makes it so exciting for novelists? "We're rediscovering London's sense of stoicism and London's sense of humour," he replies. "That ironic, dark, twisted sense of humour that is able to accommodate all these differences without us ever killing each other."

And on that note of supreme optimism I leave him to his little shed; to have big thoughts on even bigger subjects.