Interview: Ann Cleeves - Every contact leaves a trace

She smiles, says that's great, and off we head for Lerwick. She'll be reading from the latest novel in her Shetland Quartet there tonight. She'll tell her friends then.

Every writer will tell you that you can never count on TV deals coming off, but I've a hunch this one – with Dominic Minghella's Plain Vanilla production company – will be different. In 2006 Raven Black, the first novel in Cleeves's series featuring her Shetland detective, Jimmy Perez, won the world's biggest prize for crime fiction. Nine years before that, winning the same award for Black and Blue transformed Ian Rankin's writing career, quadrupling his sales and turning Inspector Rebus into Britain's favourite fictional detective. Could the same thing happen to Perez?

To find out, I've read all three of her Shetland novels and set out on his tracks. I'm in Shetland to find out how much or how little of Perez squares with the realities of island life. He's already a wee bit exotic on account of his first Fair Isle ancestor having been a shipwrecked sailor in the Spanish Armada. But just how credible is he, and how realistic are his cases? I'm going to check him and them out by talking to islanders, soothmoothers, strangers in bars, and at least one real person who's made it into the Shetland Quartet. But I'd better start with the police.

Like me, Ann Cleeves began by talking to Bob Gunn, a retired police sergeant on the Shetland force. She didn't know how the island's police would handle the murder she already had in mind. "We'd been birdwatching at Clickimin Loch just outside Lerwick. It was a stunningly beautiful, cold day – snow on the ground, a huge orange sun. We saw three ravens, incredibly black against the snow and I thought – because I'm a crime writer – what if there was blood as well? The victim would be like the Brothers Grimm described Snow White – 'hair as black as ebony, skin as white as snow, lips as red as blood ...' "

At first, she thought it would just make a short story. Turning it into a novel would surely be presumptuous for an Englishwoman, no matter how much she loved the islands. But a friend at Shetland Arts told her not to be ridiculous, that the islands had been almost completely ignored in fiction published by the mainstream London houses (Rankin's Black and Blue being a rare exception), and fixed up a meeting for her with Gunn.

"He was lovely. I asked him, would the local cops deal with it and he said, 'No, no, you'd bring a team in from Inverness.' And I thought immediately, that's great. You'd have a local cop here who's done nothing much apart from drunk driving and brawls in bars and there's a murder and they go and bring in someone above him. There's tension immediately." She knew straight away that she was on to something.

– Would they charter a plane to get here?

– No, there wouldn't be a budget for that, they'd just come on the first flight they could get.

– But the flights don't always get in … ?

– We'd just wait.

– So what would you do with the body?

– We'd cover it with a bit of tarpaulin and wait.

That was so easy to imagine. A dead girl in the snow. The woman who'd found the body sitting in her car, waiting for the police. A knock on the car window. "The image of a face, blurred by the mist and the muck on the glass, wild black hair and a strong hooked nose. A foreigner, she thought." Actually, no. Fran Hunter, meet Jimmy Perez, plainclothes detective inspector. By book two you'll be living together, by book three planning to get married, by book four (next year) meeting his parents on Fair Isle. Although first, of course, there'll be a few murders.

Bob Gunn has worked the docks of Aberdeen, the mean streets of Holloway, behind the door at No 10 Downing Street and for King Hussein of Jordan. In other words, he knows his way around the world just as well as he knows about life in Shetland. In the 12 years he spent there before retiring in 2002, there wasn't a single murder.

A cushy number, then? Because as anyone will tell you, this is just about the most law-abiding part of the country: about four or five cars stolen every year, maybe one housebreaking. There is a small heroin problem on the islands, but because most of the users have jobs, it doesn't spill over into shoplifting and opportunistic crime the way it does in the cities.

And this is the point at which Visit Shetland should sign up Gunn right away, because I don't think I've ever heard anyone define that nebulous word "community" as clearly as he inadvertently does when I ask him about Shetland attitudes to the police. "If someone is getting a speeding ticket, they'll thank you for your efforts in reducing the risks on the roads," he says. I burst out laughing. "What? Even drunk drivers? I hear you get a lot of them."

"They'll be respectful too. They'll understand that it's difficult for you and you're just doing your job."

"You must have been surprised the first time it happened?"

"It shook me."

Island police have to mirror that trust. The smaller the community, the more they've got to fit in, the less they can be the testosterone-charged obsessives of the urban crime fiction stereotype. They have to be subtle, empathetic, understanding. Perez, whose interrogations deploy silence instead of veiled aggression, would fit in perfectly. On an island posting, says Gunn, not fitting in – being aloof, not joining voluntary organisations, and so on – can result in hellish loneliness, which is why some in the Northern Constabulary would resign rather than accept relocation. "In Inverness, we're perceived as a backwater," says Gunn. "That's what the youngsters would say. Young police officers require very large shop frontages like Marks & Spencer where they can watch themselves drive by with their blue lights on. Well, we have no large shop frontages here."

At Lerwick police station, Inspector Rob McKillop, who moved from Inverness to take up his new job nine months ago, puts it differently. While city police have a battery of different specialisms, he says, the 38 officers under his command have to be able to do everything. Just for the record, I crosscheck. "So you never ever encounter any resentment?" "No, never."

It's gone 5:30pm. The phone in his office has stopped ringing, and he's about to start on his paperwork before heading home. I know my questions about a fictional policeman on his patch must sound surreal, but he answers patiently. "It's not a popularity contest, you know. But I remember when they were teaching us forensics, they had this saying: Every contact leaves a trace. And I say to my officers, that's the same in policing generally. You meet people and every contact you have with them leaves a trace."

HOURS AFTER ARRIVING IN SHETLAND, I'm drinking in the Lounge pub in Lerwick with a friend. I order a couple of bottles of local beer and we sit down at a table. As we finish them, two more bottles arrive, courtesy of a man standing at the bar talking to friends. We nod our thanks, drink them, then two more bottles arrive. This has never happened to me before, and when we get up to thank our benefactor, I assume he must own the bar, manage the brewery, or organise promotional offers. Not a bit of it, he says; he just wanted to buy us a drink. First contact, first trace: already I love this place.

Cleeves's first contact happened when she was 19. She had dropped out of Sussex university and had a job as a social worker near King's Cross in London. One afternoon a friend told her there was a summer job going in the kitchens of the bird observatory on Fair Isle. She didn't know where that was, had no knowledge of birds, but thought it sounded more fun than looking after angry inner-city teenagers, so caught the flight north to Sumburgh.

The boat for Fair Isle leaves from a nondescript pier a couple of miles away from the airport, and she waited for it to turn up. Hours passed. She didn't know that The Good Shepherd ferry didn't run in bad weather, but someone told her she'd better stay in a B&B until the weather cleared. She hadn't any money for dinner or lunch, but the owner fed her anyway.

The voyage was nightmarish, but Fair Isle ... She looks up, eyes warmed by memory. Fair Isle was where she met her husband Tim that first autumn, where she went back the following year. They married the year after that, had the first of three children within a year, and they've been back every opportunity since. Three decades on, that tiny island, just one and a half miles wide by three and a half miles long, has lost none of its magic. No wonder that it's where Jimmy Perez comes from, no wonder his father is the captain of The Good Shepherd: the place is as close-woven in her affections as the patterns in a Fair Isle jersey.

Cleeves is wonderfully unpretentious about her writing, dismissive of the early novels she wrote in precious moments snatched between looking after her children on the bird sanctuaries her husband managed. These books sold only moderately well, and although they always made a profit, she was edging closer towards the no-man's land of publishing's "midlist" – authors publishers have already determined are never going to break into bestsellerdom, and who are always the first for the chop when lists are trimmed.

But Raven Black changed everything. She'd often imagined what living in Shetland would be like, whether you'd still be regarded as an outsider even if you did make the move north. She'd always understood just how wonderfully uncool Shetland is, how strong its ties of communality are, how deep-rooted the sense of belonging has to be in such a place. Yes, has to be: if you don't feel it, you don't put up with the long, icy, depressive winters: you catch the plane south, tell friends you'll be back for visits and gradually forget to do so. (How long is it, I ask a friend who's lived there for decades, before islanders start to open up and trust you not to do just that? Three years? "A lot longer than that," she says.)

Somehow, even though Cleeves wrote it in West Yorkshire, not West Sandwick, Raven Black captured that central dilemma of island life. Her next Shetland books, White Nights and the new one, Red Bones, showed a similarly sure touch: outsider she might be, but in them, as well as providing a riveting plot, she also captures some of the islands' lure: the communality of the Sunday teas, the preparations for Up-Helly-Aa, the wild beauty of the place, with its unpolluted seas and meadows blooming with wildflowers.

"There's another thing I've always loved about Shetland," she says. "The gossip here is better than anywhere else in Britain. People get so bored, they make dramas to entertain themselves, and gossip is how you do that. Wherever you go, people will tell you what's going on in the croft next door or what has happened last week or who was coming in on the boat or selling beasts to the abattoir – all that. And gossip is what writers do, telling tales about people."

That same interconnectedness extends into the past. Shetland's Viking heritage is both extensive – Unst has a greater density of rural longhouses than anywhere even in Scandinavia – and deeply treasured. Val Turner, Shetland's lead archaeologist, who has a key cameo role in Red Bones, agrees that her subject matters more on the islands than anywhere else in Britain. At Lerwick library, where I hear her give a talk on a medieval murder, she is introduced as "our archaeologist": the island's possessive pride is immediately obvious.

Unsurprisingly, perhaps, she's a fan of Cleeves's Shetland Quartet: Jimmy Perez's investigations of the present have, she says, some echo in her own work uncovering broch village sites like Scatness, once all but invisible on a hillside, now dug out 15 feet beneath the surface, dated to around 400BC thanks to carbonised grain (every contact leaves a trace, remember) and providing clear evidence of how hundreds of Iron Age Shetlanders once lived. "I think Ann gets Shetland absolutely right," says Turner. "The geographical locations have been changed, so you find yourself twisting the geography around to work out where things might have happened. But emotionally, they feel accurate."

And Perez? How real is he? How gripping are the novels, how compelling will any TV series be? Perez is, I think, rooted in the islands. He's fallible, not over-idealised and heroic. He makes mistakes, asks the wrong questions. As his girlfriend Fran points out, he's emotionally incontinent, more like a social worker or a priest than a hard-bitten copper. He knows he sometimes gets out of his depth. He is, in short, believable.

Then there's the setting. One of the reasons Truman Capote's In Cold Blood is such a classic of non-fiction crime is that it shows the effect of violent crime on a society (west Kansas in the late 1950s) that had grown used to trusting – and welcoming – strangers. Shetland is such a place; my own first contact and Ann Cleeves's made that immediately obvious to both of us. Its geography, if nothing else, gives it a sense of community as enviably deep as it is rare. Its scenery is spectacular. It is, to all apart from its inhabitants and the 60,000 (not such a huge number) tourists who visit each year, alluringly unknown. It's almost foreign, like Bergerac's Jersey, but more egalitarian, more law- abiding, more dramatic, more rugged, more extreme, more isolated. Oh, and did I mention that the novels are rather excellent too?

Red Bones, the third book in Ann Cleeves's Shetland Quartet, is published by Macmillan, priced 16.99.