Inside a city of dreams: Sebastian Faulks on money, morality and modern London

Strange as it may sound, the much-loved and super-selling novelist who sits over a cup of tea on a peaceful sunny afternoon in a Notting Hill café-bar is about to publish his debut. His debut, that is, as a chronicler of contemporary life in all its frequent strangeness and occasional savagery. Sebastian Faulks's children found ludicrous the idea that his 2007 novel Engleby, rooted in the Seventies, counted as "modern". For last year's vastly popular excursion into James Bond territory, Devil May Care, the temporary "Ian Fleming" returned to the late Sixties. And, of course, his "French trilogy" – The Girl at the Lion D'Or, Birdsong and Charlotte Gray – transformed his perennial tendresse for past and present life across the Channel into a trio of historical fictions that recruited millions with a sturdy and seductive blend of epic and romance.

Now an agelessly relaxed 56-year-old, casual in pale jeans and plum shirt but crisp, sharp and often pointed in his answers, Faulks contrasts his wide-eyed rapture on a first trip overseas with his children's seeming indifference. "When I first arrived abroad in France, when I was eight, my eyes were on stalks through the window. This is a French tree! This is a French road! They speak a different language! Whereas my children are just looking down at the screen, flicking their thumbs." For Faulks, this plunge into alternative realities that rival the external world gives both documentary backdrop and thematic ballast to A Week in December (Hutchinson, £18.99). His eighth novel gazes long and hard into the heart and mind of Britain today – and comes back to conclude that there's almost nobody at home.

As it binds seven central characters (one, not coincidentally, a Circle Line Tube driver) into a web of frayed or firm connections over seven pre-Christmas days in London in 2007, the novel dramatises one "closed system" of knowledge, feeling or conviction after another. From the "fantasy finance" of the super-rich hedge-fund manager to the young Islamist militant's "pure exhilaration of belief" via the Tube driver's addictive role-play website to the bored teenager's virtual football-management game, we move through an alienated, hi-tech, low-contact metropolis where "a kind of functional autism was the ideal state of mind".

At the extreme end of this network of absent-minded fellow-citizens lies the schizophrenic whose "very fierce and very structured" world-view feels, in this context, more mainstream than maverick. And, for comic relief, a poisonous little nerd of a book reviewer plots revenge on his foes and cultivates his "crystalline, insoluble bitterness".

Often edgily satirical, sometimes deeply affecting, A Week in December grasps its headline motifs – from the bankers' greed to the jihadis' hatred – with the strong and supple hands of a master of high-definition, multi-dimensional realism. Yet, for all the high comedy and sumptuous social detailing enroute, and a late shift in the direction of happy-ish endings, the underlying bleakness in this dystopia of urban solitudes may startle Faulks's fans.

A few years ago, he had planned "a dirty great big Dickensian 700-pager" of a London story. He cites novels such as Bleak House and Our Mutual Friend –along with such New York observers as Tom Wolfe and Jay McInerney – as forerunners. Gabriel, the poor but honest lawyer who gives A Week in December its moral compass, loves reading Balzac – whose Parisian panoramas must also lie somewhere in the mix.

Even then, says Faulks, "It had been growing on me for a while what a weird time we had been living through financially." Through west-London neighbours (Faulks lives in in Holland Park) and parents at his children's school, "I came across a number of people who worked in financial servicess. And I was aware that the amount of money being earned had become decoupled... it had lost contact with reality. I knew people who were getting bonuses of five or six million. Just unbelievable."

Born near Newbury in 1953, the son of a decorated soldier (MC in Tunisia) who became a solicitor and judge, and brother of a highly esteemed QC, Faulks went to Wellington College and studied English at Emmanuel College, Cambridge. He worked as a journalist – becoming the first literary editor at The Independent in 1986 and later deputy editor of its Sunday sister - before fiction became a career as well as a calling in the early 1990s. Front line, front page, bar, bench and bookshelf: this classic cluster of vocations may - sometimes - prove lucrative, but few (even future QCs) tend to follow them for the cash alone. Among its virtues, A Week in December captures the anguish and bewilderment of an English professional class in a disorienting time when – as Gabriel says - "somehow money had become the only thing that mattered".

Faulks himself has friends in the lavishly rewarded niche of high finance "who are highly cultured, civilised, generous people. But at the same time I also know people who are not particularly gifted and not particularly nice." From the rougher end of this spectral trade he has fashioned the wholly fictional but spookily credible John Veals: a hedge-fund monomaniac with "no interests outside the acquisition of money". Veals's brilliantly charted strategy to bring down a major bank – a devious undercover trade which Faulks ran past several City insiders to ensure its authenticity - unrolls throughout the novel. As cold, impassive and deadly as a coiled rattlesnake, Veals will endure as the epoch-defining villain of early 21st-century British fiction.

Meanwhile, Faulks found that his tech-savvy kids (three, who now span the teenage years) always had "their fingers or thumbs on the screen in some shape or form." Glimpsing his son watch Chelsea as he texted a friend and played Football Manager online, "I realised that it was possible that the movement of his virtual team meant more to him that the performance of his real flesh-and-blood team". So "This theme began to emerge of how we are living in a world in which we have become detached from, or separated from, real life".

So far, so 2006. Then Faulks took his break with Bond. When he came back to what passes for reality, "the whole world had changed: the banks were collapsing, we were facing Armageddon, and I understood then that I couldn't make this book right up to the moment." It focuses on one week at the end of 2007, when distant thunder can be heard but the storm has not struck. "I chose that time because then the writing's on the wall, and it should be clear to anyone half-sensible that the game is up, but they're still going on."

Faulks's intensive research in the undergrowth of funny finance led him to conclude that "You cannot pin the blame on any one person or group of people. The ratings agencies failed. The accountancy firms failed. The hedge funds were rapacious – though nothing they did was really illegal. But I think everyone would agree that short-termism was a serious problem". The novel veers between fascination with the mysteries of free-floating wealth and a bass note of controlled fury.

Faulks doesn't do fury, at least not over tea in Notting Hill, but he does do calm, withering irony. As we consider the bounce-back of bonus culture in the City, he says that not only are we "all going to be paying out of our increased taxes for ten, possibly 20, years for the excesses of what banks did. That is a brutal and very angry-making fact" - but also that "the only people immune from the backlash are the people who generated the problem."

As if the madness of the banks were not enough fuel for a big-engined social novel, A Week in December also takes on the "closed system" of jihadi militancy. Hassan, son of the affable lime-pickle baron "Knocker" al-Rashid, falls in with a violent subculture via an east London mosque. Faulks admits to knowing little about Islam before he began but, as with the City intrigues, set to work with his habitual diligence.

His reactions to the creed he tried to fathom have already caused a small stir, so let's make things plain. Three of the four main Muslim characters – Hassan's devout, loving parents, and his smart, funny, non-religious friend Shahla – are drawn in wholly affectionate and admiring tones. Even the hot-headed Hassan proves, as Faulks says, "troubled, but basically a nice guy".

Yet sane and shrewd Gabriel reads the Qur'an and is given the same response to its divinity as – according to Evelyn Waugh – Randolph Churchill had when he read the Bible: "What a bastard". Faulks's reflections on his research had three main elements. First, he found the sacred text "problematic". "If you were dating Old Testament, New Testament, Qur'an, blind in a kind of undergraduate exam you'd put the Qur'an as the earliest."

For Faulks, the second issue "reflects very well on Islam: it's an incredibly demanding religion. It's spiritually far more evolved than Judaism or Christianity as I understand either of them... Islam does offer the total explanation of every breath and every thought. It is in that literal sense a fundamentalist religion. It requires a fundamental and total belief from all its adherents. 'Fundamental', of course, doesn't mean to say aggressive, still less violent".

And third, "Islam as this super-demanding, very pure religion doesn't really approve of any of the societies in the world in which its adherents live". So "It is, spiritually, a much more demanding religion. And it is also, politically, more discontented if you look at it logically and properly. Therefore to be a happy Muslim family in this country - or in any country - requires a greater degree of compromise than it does to be a happy Jewish or Christian family. That's as I understand it."

At the other pole from the jihadi "Vanguard Force" that Hassan joins lies the sneery Private Eye-style magazine The Toad, anonymous outlet for the venomous hack R Tranter, and a symbol of the mocking undertow to secular British culture. The novel feels divided over Toad-style irreverence, both a bulwark against fanaticism and a barrier to thought, as is its author.

Faulks worries that the "self-satirising" nature of British society might, apart from its healthier outcomes, stunt the growth of ambitious, non-ironic fiction about modern life - as written in the US by a Bellow, Roth or Updike, "novelists who look out of their window and see the life around them, then produce interesting, entertaining but weighty novels about it." If Roth invents a glover from Newark, he can trail a tragic history in his wake, but "If I said my main character is a glover from Croydon, people start to snigger a bit."

To attempt a full-spectrum fictional portrait of today's Britain is "like trying to put your pen down on top of a snooker ball," he thinks. "It slides off one way or another. I set out to write a less satirical book than I ended up writing." With satire in Britain, "you find it happening to you" willy-nilly.

In A Week in December, reality TV offers the novelist one plump target for satirical spleen. The It's Madness show sends a group of patients with psychotic illnesses into a Big Brother-style house to compete for access to top-dollar private treatment. Unsurprisingly, on-screen tragedy ensues. Faulks pitched these scenes "just beyond" the limits of the possible, but still "the American publisher was appalled... They seem not to have the equivalent there".

If It's Madness plays pychosis for sickened laughs, then Gabriel's schizophrenic brother Adam - and the voices he hears - becomes the archetype of ruling delusions in a book stacked to the brim with full-time fantasists. After his 2005 novel Human Traces, which dug deep into the early history of psychiatry, and the unsettling first-person case study of Engleby, A Week in December completes – I suggest – a sort of trilogy of novels about detached mental states. Faulks denies any such intention, but says he noticed while creating Adam that "this was the third book in a row I'd written the word 'schizophrenia'". He adds that "I do find it unbelievably fascinating. I do think that schizophrenia is the human illness."

His novel has a painful jab at "middlebrow interviewers" who assume that every person and action in fiction derives from the author's experience. So, rather diffidently, I ask what first drew Faulks into the terrain of psychosis. "The first schizophrenic I met was my godmother's son," who "absolutely typically" became ill aged 20, as a "bright, nice" university student.

From his school football team, "two out of the 11 became paranoid schizophrenics. One of them has barely been out of hospital since age 18." A neighbour's son also fell victim to the condition that descends on one human in every hundred – an evolutionary by-product, some theories suggest, of the super-sized brain that allows us to plot suicide bombings, short-sell banks and write novels. "So it's been a fairly persistent thing... It's very, very interesting, and people don't really want to know about it. If one in a hundred dogs imagined they heard barking all the time - that's a pretty strange creature."

From hedge-fund boardrooms to online chat-rooms and teenage bedrooms, A Week in December shows us these strange lonely creatures both as they succumb to their delusions, and - with slowly rising confidence - battle to overcome them and connect again. Broad in its canvas, bold in its themes, the novel also had to forge – another first for Faulks – a way of speaking that captured both these looming big ideas and the chatty informality of now.

"One of the difficult things," he says, "was trying to get a model sentence that was modern, colloquial, conversational, but at the same time sufficiently flexible to take on some of these serious concerns... I hope that people won't say when they read it, 'Blimey, his style's changed a lot'."

Those readers who savoured novels such as Birdsong as a shared quest for value through narrative in a mad and perilous time might answer - no, it hasn't, all that much. Faulks, every inch the upright and conscientious professional, still frets that his semi-comic saga fails to strike the note of high seriousness he reveres in that American trio of giants: Bellow, Roth, Updike. "I still want to do Augie March, The Human Stain or Rabbit," he says, a little wistfully. But the author of A Week in December has already built and peopled a far-from-virtual world of his own.