After falling into crime writing by accident, bestselling Norwegian author Jo Nesbo has taken his mercurial central character, Detective Harry Hole, on a dangerous, murder-filled journey where both the cop and his creator are prone to breaking the rules, he tells ARMNTA WALLACE

UNLESS YOU'VE been on another planet for the past six months, you can't fail to have noticed that an awful lot of people are reading books by the Norwegian crime writer Jo Nesbo. It started with The Snowman, which appeared to be mandatory reading across Ireland and the UK during last year's pre-Christmas cold snap. And Nesbo's new book, The Leopard, prowled straight to the top of the bestseller lists, where it's currently being joined by his entire back catalogue.

There are plenty of good Scandinavian crime writers – Karin Fossum, Arnaldur Indridasson, Karin Alvtegen, Camilla Lackberg and Hakan Nesser, to name but five. So why has Nesbo suddenly catapulted into the international bestselling stratosphere? What’s the appeal of his books in particular?

“I don’t know,” he confesses, with a gesture that’s half-grin, half-shrug, “and I’m not sure if I want to know. If you analyse too much . . . I think that my writing would be more self-conscious. I imagine myself with two good friends when I write. Those are the people I write for.” They suit the rest of us pretty well, too. You don’t so much read a Jo Nesbo book, as climb inside and pull the lid down on top.

For a guy who writes such scary stories, Nesbo appears laidback, softly spoken and calm. At the same time, he exudes restless energy and, somehow, a whiff of the great outdoors: he has the look of an Arctic explorer who has strayed into the lobby of Dublin’s Westbury Hotel in order to secure funding for some finger-freezing expedition.

When the waitress brings a tiny cup of espresso he springs forward out of the couch, causing her to retreat an inch or two in alarm. But he’s just after the sugar, fishing two brown cubes out of a tiny white bowl and stirring them into the steaming liquid.

On the table beside the coffee sits The Leopard, all 613 paperback pages of it, its cover emblazoned with the words "Over five million books sold worldwide" and, in a discreet but unmissable circle of bright green, "the next Stieg Larsson". It must be more than five million now, surely? Nesbo shakes his head. "Yeah, probably," he says. "I have no idea." But he didn't set out to be the new Stieg Larsson – did he? "Definitely not," he says. "I didn't set out to be any kind of . . . I mean, I didn't idolise any Scandinavian crime writers. Actually, I didn't read any Scandinavian crime writers." What did he read? He shrugs a loose-limbed shrug. "I read books. Charles Bukowski . A Clockwork Orange.Frank Miller, the graphic novelist. There were a couple of crime writers that I liked. Jim Thompson and, also, Lawrence Block."

NESBO'S FIRST NOVEL, The Bat Man, appeared in Norway in 1997 – much to the author's surprise. "The reason I started writing a crime novel was that I was pretty sure my first attempt at writing a novel wouldn't be published," he explains. "So I thought, 'Okay, let me write something that I know how to finish.' So that I can get it over with quickly, and send it in, and then hopefully I will receive a polite refusal saying; 'Okay, we can't publish this, but we see some talent here so please send us something new if you plan to write something else.'"

In the course of writing The Bat Man, however, he changed his mind about the crime genre. "I realised the crime novel was something different to what I had thought," he says. "I discovered that it sort of made it possible to have more intimate dialogue with the reader. Because there are rules, and there are expectations – and just by abiding by those rules, or breaking the rules, you can make something happen. And that was interesting for me.

“It’s sort of like etiquette in social life: if I say, ‘How do you do?’ or if I don’t – it’s significant. There are rules to the novel, also, but the rules aren’t as strict as with the crime novel. I discovered that I liked that. They were rules that you could play around with.”

The Bat Man, by the way, is currently being translated and will be published here next year. Having written the book almost by default, why did Nesbo stick with his central character, the mercurial, difficult, alcoholic detective Harry Hole? "When I started to write my second novel, I wasn't sure if it would be a crime novel at all," he says. "But then I said, 'Yeah. I like him.' At that time he wasn't probably developed as a character, but I liked the idea of a series. So in the end I stuck with Harry. And after the second novel, I knew. I'm interested in this character and now, for sure, I'm going to use him again. By my third novel, The Redbreast, I finally knew who he was."

The Leopardis the eighth book in the series. Traumatised by the Snowmanserial killer case, which almost killed his partner Rakel and her son Oleg – who have fled Norway without telling him where they've gone – Harry is in Hong Kong, sleeping rough and seeking refuge in the oblivion of opium. Meanwhile, back in Oslo, two young women have been found drowned in their own blood, riddled with inexplicable puncture wounds: and Harry's father is seriously ill. A young detective called Kaja Solness is sent to drag the reluctant Harry back to the real world.

For most of the journey he’s petulant and taciturn: then, as they drive through the Ibsen tunnel into the Norwegian capital, his mood changes. “It was at that particular moment that he felt it. A huge, unalloyed pleasure at being here. In Oslo. Home. The feeling was so overwhelming that for a few seconds he was oblivious as to why he had returned.”

Soon, however, Harry is beginning to wonder if he shouldn’t have stayed in China. The detective’s love-hate relationship with Norway plays a major role in the series. And, presumably, reflects the attitude of Harry’s creator? Nesbo’s pale blue eyes sparkle with amusement. “Yeah,” he says. “You can pretty much assume that Harry’s views when it comes to Norway are mine.”

Although Nesbo worked – successfully – as a stockbroker before he began to write fulltime, he hasn’t brought the financial world into the plots of any of his books. Perhaps it’s just too scary, I suggest? “Well, I tend to use milieux that I may know a little bit, but where I’m not an insider,” he says. “I mean, I played football – but I don’t think I would ever write a novel that would take place inside a soccer team. And I played in a band, but I wouldn’t fancy to write a novel from a band member’s perspective. I’m not sure why. It’s like, if you write about something that you know a little bit but not too well, you can still have the view of the outsider. And so you can identify with the reader. And it’s easier to describe it.”

To say he played football is a typical Nesbo understatement. He played for a team in Norway's premier league until he tore cruciate ligaments in his knee at the age of 19. The band he mentions is the alt-country outfit Di Derre ( Them There), whose second album topped the Norwegian charts – and with whom he still plays when he can. "We don't record, and I don't write songs. I write, like, one song a year. But during the summer it's like a holiday with old friends – we travel, and we play festivals for a bit, and it's great fun. And we still have an audience who love to hear the old songs, so that's great."

If Nesbo continues to rise on the international literary stage, the band can look forward to sold-out gigs for summers to come. Nor can Harry Hole murder tours around Oslo – the Munch Museum, the Frogner Park, the Holmenkollen ski jump – be far behind.

What, though, does the future hold for Harry himself? “His near future is bleak,” Nesbo predicted, a couple of books back, in an online interview, “after that it’s getting worse. And then it’s going to hell.”

“I constantly give him moral dilemmas,” Nesbo says, “and he doesn’t always do the right thing. But in the end he will. For me, what’s interesting in the story is not whether the murder is solved. Of course, that is interesting too: who did it? But what’s driving the story, or at least the series, is the moral choices that your main character is making.

“That’s not about solving the murder, and it’s not about whether he’s going to survive physically. It’s about his eternal soul. Is he eventually going to heaven or hell? That’s what I’m concerned about; and hopefully, what my readers are concerned about. Whether he’s going to stay the hero.” Er, and get back together with Rakel and Oleg? Nesbo smiles enigmatically. “That too.”

Nesbo number nine is due for publication in Norway this summer, and in English in 2012. Will it be as sinister and scary as books one to eight? He pretends to think for a moment. "It's probably not as violent as The Leopard," he offers. Then the blue eyes flash. "But hopefully just as scary."

The Leopardis published by Harvill Secker

And for something completely different . . .

WHAT WITH women drowning in their own blood and creepy serial killers using their victims' clothing to decorate snowmen, you mightn't think Jo Nesbo the right kind of writer to be in charge of a children's book. Yet his Doctor Proctorseries of illustrated stories is wildly popular in Norway.

With which age group? "I'd say smart six-year-olds," he says. The first book is called Doctor Proctor's Fart Powder. You get the idea.

Why did Nesbo want to write for children?

He looks abashed. "To me it always sounds like a bad idea when you have an artist suddenly writing a song for children, and it's because he has just become a father or she has become a mother," he says. "But that is the case with me, too."

After a summer of telling his daughter stories about the Doctor Proctorcharacter every night, he decided it was time to write them down. "So suddenly I had a whole bunch of young readers, and they wanted another book, and now it's three," he says.

A fourth is on the way. Baby Nesbo, imagine. Let's hope they put kids to sleep, rather than wake them screaming . . .