In the city of dreadful nights

Behind the cosy images on the shortbread tins, Edinburgh harbours horrors of deprivation and crime - and that's where you'll find Ian Rankin's detective, Rebus

The opening titles of Rebus, ITV's new adaptation of the Ian Rankin detective novels, contain a series of picture-postcard views of the heritage-industry Edinburgh familiar to most of us - all impressive stone carvings, imposing statues and elegantly crenellated municipal buildings decorated with such uplifting phrases as "let there be light". The drama that follows, however, shows us a very different Edinburgh, replete with hookers, hoods and heroin dealers. The city is almost like some mythological creation: half theme park, half den of iniquity. Edinburgh is a tale of two cities.

According to Rankin, the Scottish capital has always had this duality. It was a Jekyll and Hyde city long before the Edinburgh author Robert Louis Stevenson dreamt up that archetypal split personality.

"Edinburgh has all the tension of a museum piece with real social problems simmering just below the surface," says Rankin, an appealingly dishevelled figure. He is visiting a location at a disused psychiatric hospital on the outskirts of Edinburgh to see what the co-producers, Scottish Television and Clerkenwell Films, are making of Rebus.

"When I moved here from Fife in 1979, I was immediately aware of two Edinburghs: the city fathers, World Heritage Site tourist centre was juxtaposed with the city that in the Eighties had the highest incidence of Aids in Western Europe. Oxfam declared one Edinburgh housing estate the equivalent of a Third World country.

"It took the film Trainspotting to make people realise that there's more to Edinburgh than the castle and shortbread and fine malt whisky. As a student, I lived in the low-rent areas of Edinburgh. When I travelled into the centre and saw tourists taking photos of Greyfriars Bobby, I felt they weren't seeing the city I knew. It made me want to write a book about a more three-dimensional place than they were seeing. So my first Rebus novel, Knots and Crosses, was a reworking of Jekyll and Hyde." (In his turn, Stevenson was influenced by the true story of Deacon Brodie, who led a double life Superman would have been proud of: respectable carpenter and city councillor by day, dastardly thief by night. Brodie was eventually hanged on a gallows that - by a cruel irony - he himself had designed).

Like Stevenson, Rankin uses the physical to reflect the spiritual. "When the Edinburgh city fathers built the posh area called the New Town, it immediately created a schism, and that schism is mirrored in all of us," he continues. "We may have a superficial probity, but underneath all these vices are yearning to come out. It's Jekyll and Hyde all over again."

The twist is that in Rankin's version, Jekyll is not a doctor but a policeman. "I had no interest in crime fiction, but I thought that it was a nice conceit. The police have access all areas; they're in the elegant offices of the Lord Provost one minute and on a syringe-strewn estate the next. Rebus has an anarchic edge to him; he's more likely to give a criminal a break than a corrupt lawyer. He's attracted to the criminal milieu. The dark side that he represses may end up winning out." Rankin admits that "I have elements of Rebus's schizophrenic personality. I'm a quiet family man with two kids who, given half a chance, goes for long night-time drives by the docks."

All of which makes for a pretty damaged central character. In the drama, the first time we see DI John Rebus (played by the brooding John Hannah), he is going for a lone midnight ramble through the pouring rain to contemplate a particularly gruesome murder by a Bible-quoting psycho killer dubbed "The Disciple" in the tabloids. "You know an investigation's in trouble when some hack invents a nickname," Rebus intones in his noirish voiceover.

"Rebus has already had one-and-a-half breakdowns," Rankin says by way of explanation. "I didn't like the fact that in more traditional crime fiction the cases never changed the detectives investigating them. In real life, they're always affected and they become obsessed by unsolved cases. Detective fiction shouldn't be a happy-go-lucky romp."

But that's just one reason why Rebus is such a troubled soul. "I gave him this huge past," Rankin chuckles. "His father was a hypnotist, his brother was a junkie, and Rebus himself was kicked out of the SAS. I also gave him this silly name which means "picture puzzle" in Greek. I thought I'd made it up till I met a guy in a pub called Joe Rebus who lives in Rankin Drive, Edinburgh. Thankfully, he's not a detective; he's a central heating engineer.

"Rebus is a character who's hard to pin down. People say he's the only character in fiction who actually makes them feel healthy. It's always a bad sign if a writer takes a character on holiday. Rebus would never travel; he doesn't work well in an environment he doesn't understand. He's complex, and I haven't unpeeled all his layers yet."

What is perhaps most plausible about Rebus is that, unlike a Mountie, he doesn't always get his man. "He's deeply flawed," Rankin continues. "He doesn't catch the villain every time, and he is often more dissolute at the end of a case than he was at the beginning. People get a thrill from seeing someone who is hammered by life but who keeps getting up and coming back for more. The good thing is Rebus doesn't do it like a Hollywood hero who's had his feet chopped off but still keeps chasing baddies and getting the girl. He's more human than that."

Rankin was born in Fife in 1960, and his first job was in a chicken factory. He soon found out, however, that "there was no way I was going to spend the rest of my life killing chickens", so he went to read English at Edinburgh University. Since graduating, he has had a variety of jobs including grape-picker, swineherd, taxman, alcohol researcher, hi-fi journalist and punk musician.

While studying for a PhD on Muriel Spark, he decided to write his own novel, and subsequently his 11 Rebus books have made him something of a publishing phenomenon. Each novel sells in excess of a quarter of a million paperback copies, and at one point last year, he occupied eight slots in the Scottish bestsellers' top 10. The doyen of modern crime writers, James Ellroy, has dubbed him "the King of Tartan Noir", and inmates of Wandsworth Prison, where Rankin's books are the most popular, appear to agree.

Fans can even take a guided tour around the sites of the sleaziest dives and grisliest murders in the novels. Rankin reveals that "visitors go into Rebus's favourite bar and ask 'are you the rudest barman in Scotland?' 'Yes.' 'Can I have your autograph?' 'No, fuck off'.''

But success comes at a price. Like Rebus, Rankin finds that his work gets under his skin. "I'm a news junkie," he says. "My wife despairs of me because when she picks up the paper it's full of holes where I've cut out stories. I took three out of The Scotsman just this morning. Real life is a great source of stories, but sometimes it bites back. I wrote The Hanging Garden in France, thinking 'what if I invent a suspected Nazi war criminal who is living in Edinburgh?' When I came back here, I discovered there was a real-life suspected Nazi war criminal living in Edinburgh."

As he makes to leave, Rankin surveys the grim Nissen huts of the psychiatric hospital and sighs: "I don't much care for this place. It's a cross between a death camp and a sci-fi movie where everyone mysteriously disappears. In fact," he adds, suddenly brightening, "I think I'm going to use it in the next book."

'Rebus', ITV, Wednesday, 9pm