"Where is it?"

"I'll tell Abbie when I see her, face to face."

"It's difficult, Matt. She can't get away right now. I'm here for her."

"Sorry. You'll have to do better than that."

So eventually he relents and tells me the story.

"In the last couple of years," he begins, "Abbie's role at the art dealer's where she works has been to go around the UK to auctions, regional dealers and house clearances, looking for bargains."

"Like Antiques Roadshow," I suggest.

"Yes. She's got a pretty good eye for it and she's been quite successful, though her boss, a pompous old git, hasn't recognized it in her pay. Anyway, a couple of months ago she came across an elderly lady who wanted her to look at a small sketch she owned, of the head of a bearded man. She'd inherited it from her mother, who'd been in service to an eccentric lord up in Scotland, and he'd given it to her when she retired. She a.s.sumed it was a portrait of one of his ancestors, and hoped it might fetch a hundred pounds or two. But Abbie had seen a very similar sketch once before, in Turin in Italy, a self-portrait by Leonardo da Vinci."

"Leonardo? You're joking!"

"No, I'm not. It looked very like the real thing and Abbie told the owner that it could be worth much more, possibly several thousands, but she would have to take it away to authenticate it. The old lady was delighted and agreed. When she got to London Abbie used all the expertise at her disposal and discovered a fingerprint embedded in the red chalk material of the drawing. She compared it to a fingerprint that had been found in da Vinci's painting of St Jerome in the Vatican, and got a match."

"Wow. What would it be worth?"

"Thirty, maybe forty million dollars."

I'm stunned. "Her boss must have been delighted. Will she get a good commission?"

"No, he doesn't give her commission, just her basic salary, maybe a modest Christmas bonus. And he wasn't delighted, because she didn't tell him."

"Oh?"

"Matt, this is a once in a lifetime discovery, a moment of truth. If she tells them, the old lady will get more money than she knows what to do with and will die next year and leave it all to the dogs' home, and Abbie's boss will stuff himself with even more big lunches and French champagne than he does already and have his coronary a little earlier than otherwise."

I'm not sure I like this story. It doesn't sound like Abbie at all. Has London changed her? "So what did she do?"

"She came to me for advice."

"And who are you, exactly?"

"I work for Scotland Yard, Fraud Squad. Abbie and I met during a forgery investigation last year, and got on well. When she told me the story I advised her to keep the Leonardo, give the old lady five thousand and buy a few extra paintings for her boss, and both would be delighted."

"Only five thousand?"

"Abbie wanted to give her more, but the old woman would have told everyone and word would have got back. Really, she was over the moon with that."

"You advised Abbie not to tell the owner that she had a multimillion-dollar masterpiece on her hands?"

Rich looks uncomfortable. "It was only Abbie's knowledge and expertise that made it that, Matt. I thought she deserved the profit, not the owner or her boss. Then I told her she had to find a special kind of buyer, a collector who wouldn't care about where it came from as long as the scientific tests proved authenticity, which the fingerprint certainly did. And I thought I knew of the perfect customer, a Swedish billionaire recluse by the name of Martin Graven, who is reputed to have bought stolen artworks in the past. He lives on his private island east of Stockholm, on the edge of the Baltic Sea. It's called Blod o, which means Blood Island apparently it was the site of a ma.s.sacre during the Thirty Years War back in the 1600s."

I sit back, trying to digest all this. "So you're a cop with Scotland Yard, and you're helping Abbie to break the law?"

"It's only a technical breach, Matt, and like I said, this is a once in a lifetime chance for Abbie. She'll walk away with half the true value of the sketch and set up her own gallery and show the lazy b.a.s.t.a.r.d she works for."

"And what do you get out of it, Rich?"

"I'll be her business partner, mate, maybe more than that if things work out I'm very fond of Abbie as it happens. And who knows, we'll probably need a bright lad like you to open an office for us down under." He gives me a friendly pat on the shoulder.

"But something's gone wrong, hasn't it?"

He frowns. "Yeah. I knew that Graven had a reputation for being ruthless, but I hadn't counted on him being quite such a b.a.s.t.a.r.d. The problem in this situation is making a deal without anyone getting ripped off I mean, you can hardly complain to the cops afterwards. So we decided that one of us would come to Sweden to negotiate with him while the other waited for the all clear. Abbie had to be the one to come over, because only she could convince him of the technical verification, but Graven's made her a virtual prisoner on his island, and he seems to be very well informed about us, including our plan to have you smuggle the drawing into the country."

"You mean ... he's forced it out of Abbie? Tortured her?"

He hesitates. "I don't know. But I'm going to have to go to his island to get her out of there, and I can't take the drawing with me or he'll just take it and kick us out, or worse."

I'm appalled. "He'd go as far as murder?"

"For something like a Leonardo original self-portrait as good as this one, I reckon he'd do pretty much anything."

"Then give it to him!"

"First we have to get Abbie out, and the Leonardo is the only lever we've got. It's hidden behind the inside lining of the back cover of the book. You're sure you have it safe?"

"Yes. I had to hide it when those two thugs came after me, but I can get to it anytime."

"Then we've got to keep you out of trouble. You'll have to find another hotel."

"Right, and I can still keep in touch with the mobile phone Abbie left for me."

"Let me see that." He examines it. "You've had it on all the time?"

"Of course."

"That's probably how they've been able to keep tabs on you." He switches it off. "Come on, pack your things."

We go down to the lobby and pay Mikael, asking him to call a taxi for us. It pulls up at the door and we slip into the back and head into the commercial district across the river. The cab drops us outside a Vodafone shop where Rich buys me another mobile, and then we walk through the shopping streets until we find a small commercial hotel where I check in. We shake hands.

"Good luck," I say. "Give Abbie my love when you find her."

"Sure. Don't worry. You just wait for my call," and he strides away, leaving me feeling worried sick.

I don't hear from Rich again that day and the following morning I decide to go back to Gamla Stan to check on Abbie's book in its hiding place on the shelf of the antiquarian bookshop. On the way I call in at a department store in the centre of the city and buy a parka and a cap in the hope that the skinheads won't recognize me if they are still out there. It's another cold crisp day with dark clouds threatening the blue sky as I walk back across the bridge and up the cobbled streets of the old town. I turn a corner and there is the bookshop in front of me. A small crowd is gathered outside around a man wearing a fluorescent yellow jacket with the word POLISEN printed on the back. As I approach I see that the shop door is barred by a striped plastic tape. At the edge of the crowd I ask a woman what is happening, and she tells me that the old man who owned the shop has been found murdered, the place ransacked. I work my way to the window and peer in. The lights are on and I see two people in white nylon overalls inside. The word printed on their backs is FoRMIDDAG, which I guess means forensic. Behind them the bookshelves seem undisturbed, and I can see the place where I hid Abbie's volume. But there is no red spine visible there now.

I feel suddenly sick, heart pounding. Without that book Abbie's life is forfeit. Should I speak to the policeman? Then I'm aware of a woman sobbing by my side, and when I look at her she says something in Swedish.

"I'm sorry?" I say.

"Oh, you're English? I said, poor Mr Palmgren." She wipes her eyes.

"You knew him?"

"I work here. It happened last evening, after I left. Mr Palmgren was alone in the shop. The b.a.s.t.a.r.ds must have been after the cash box, but they didn't have to kill him, did they?"

"I am sorry. I came here yesterday and I saw a book I wanted to get. It was on the top shelf, a book of Leonardo's drawings, but I can't see it now. Maybe they took it."

"Oh, I remember the one. You're out of luck. I sold it yesterday afternoon."

"Really?" I feel a tiny glimmer of hope. "I don't suppose you remember who to?"

"It was to one of our regulars. She buys a lot of our books. Her name is Vera, Vera Kulla."

"Oh. I did want that book very much. Maybe she would sell it to me."

"Well, I suppose you could try. I may have her address ..."

I hold my breath as she rummages through her bag and eventually produces a well-thumbed address book. "Yes, here we are she has an apartment in Fiskargatan. That's a street on Sodermalm."

I take a note of the address and thank her and tell her again how sorry I am about Mr Palmgren. Then I hurry away to study my Millennium map of Stockholm for the address. The map pinpoints all the places mentioned in the Stieg Larsson trilogy, and I discover that many of them are located on Sodermalm, a much larger island that lies just to the south of Gamla Stan. I head that way, crossing on the bridge that links the two islands and climbing up into the busy district of mixed commercial and residential buildings. Here my map takes me past Mikael Blomkvist's fictional apartment, and then along Gotgatan to the offices of his Millennium magazine, where I turn off into quieter residential streets towards Fiskargatan, which my map tells me was where Lisbeth Salander bought herself an apartment in the second book, The Girl Who Played with Fire.

When I reach the block I press the entry phone b.u.t.ton marked V. Kulla at the front door. After a moment a woman's voice says, "Ja?" and I give her my name and say I'd like to talk to her about the book she bought from Mr Palmgren. There's no reply, but the security door clicks open and I step inside.

I climb the stairs to Vera Kulla's front door. When it opens I'm astonished to see the girl on the bicycle who crashed into my a.s.sailants yesterday, the girl who looks so much like Lisbeth Salander in The Girl with the Dragon Tattoo movie.

I just stare at her, open-mouthed, and she steps back and waves me inside. I look around at the IKEA furniture, just like in Stieg Larsson's description of Salander's apartment.

She folds her arms. "Well?"

I say I want her to sell the book to me, and she raises a sceptical eyebrow. "Why should I?"

"It's a matter of life and death," I say. "Please!"

She stares at me for a moment, then tells me to sit down at the table. She brings two mugs of coffee and sits opposite me, lighting a cigarette and holding it up the way Lisbeth Salander would have done. She eyes me coolly. "Tell me."

I feel I'm going crazy and I blurt out, "Are you one of them? Are you working for Graven too?" although as I say this I realize it doesn't make much sense.

I take a deep breath and try again. "Look, yesterday you rescued me by crashing your bike into two thugs who were trying to rob me. Did you follow me after that? Or were you in the bookshop when I ran in and hid the book on the shelves?"

She takes a draw on the cigarette and says nothing.

Getting angry now, I say, "So now I come here and meet you again, looking like Lisbeth Salander and living in her flat. Well, I'll tell you this I wish you were Lisbeth Salander, because I could really do with her help right now."

She leans forward and says, "Tell me about Graven."

So I do, I tell her everything, including about the Leonardo drawing. It's no doubt an impulsive and stupid thing to do, but I desperately need help and I feel I can trust her, although that is probably just the illusion of her fictional character.

When I finish she gets up and brings the Leonardo book to the table and we examine the lining of the inside of the back cover. Sure enough, it does look as if it may have something hidden beneath.

Vera closes the book. "Your sister is very foolish."

I start to protest, but she goes on, "Martin Graven is an extremely dangerous man. People are afraid of him. It is whispered that he was behind the murder of our Prime Minister, Olof Palme, back in 1986, because Palme tried to put a stop to his crooked business dealings. No one has dared challenge Graven since then. There are other rumours too, of people who go to his island and do not return."

She picks up a pen and doodles his name, MARTIN GRaVEN, on a notepad, and as I watch her another unnerving thought comes into my head. "Martin Vanger was the name of the serial killer in The Girl with the Dragon Tattoo, wasn't it? It's an anagram Vanger, Graven."

"Very good," she says. "You think it's a coincidence? Stieg Larsson was a crusading journalist, very like his fictional character Mikael Blomkvist. Sometimes fiction and reality are hard to disentangle."

I shake my head in confusion and reach for the book. "Look, Vera, you understand now why I must have this. It's my sister's pa.s.sport to freedom. I'll give you back whatever you paid for it, plus something for your trouble."

"But the problem is, how do you use that pa.s.sport?" she says. "They will find you again, and when they do they will take the book and you will have no pa.s.sport left. Better that you leave it here with me. Don't worry, I won't run off with it."

That does seem to make sense I have no idea where else in Stockholm I can safely hide it, but can I really trust her?

"I saved it once before," she reminds me, and so I reluctantly agree to leave the book with her.

I leave and wander through Sodermalm, always looking over my shoulder to see if I'm being followed. I come to the Kvarnen Bar, which my map tells me is where Lisbeth Salander met the girls in the rock band Evil Fingers, and where Mikael Blomkvist and his colleagues at Millennium magazine came for a drink. They seem like real friends now, and I go inside. The pub used to be an old high-ceilinged beer hall, now done up as a trendy cafe-bar with a dance floor and resident DJ, and is busy. I order a cup of coffee and find a quiet corner to check my phone. There are no messages and I text both Abbie and Rich but get no reply, and have a sick feeling as I remember what Vera said about people disappearing when they went to Blood Island.

When I return to my hotel I have barely stepped into my room when the phone beside the bed begins to ring. I pick it up and a man's voice says, "h.e.l.lo, is that Matt?"

The voice sounds cultured, a Swede with a good command of English, a middle-aged man, I guess, quite relaxed and friendly.

"Yes, who's this?"

"My name is Dirch. I am Mr Graven's personal a.s.sistant."

I stop breathing. "Oh?"

"We have some business to discuss, I think."

"Is my sister all right?" I blurt out.

"She is perfectly well, as is Rich."

"Let me speak to them."

"One moment ..."

There is silence on the line for a long while, and then, finally, I hear my sister Abbie's voice. "h.e.l.lo, Matt. How are you?"

"I'm fine!" I cry with relief. "But what about you?"

"We're ... all right." She doesn't sound all right to me, but she goes on, "I want you to do what Dirch asks. Then we can go home."

"You're quite sure?"

"Just do what he says, please, Matt."

Dirch comes on the line. "Now Matt, I will pick you up this afternoon at five o'clock at the Museikajen quay beside the National Museum. It's just ten minutes from where you are now." "How will I recognize you?"

"Don't worry, I will know you. And of course, you will bring the Leonardo book with you, yes? Five o'clock. Don't be late."

When we ring off I call Vera and tell her what's happened. She tells me I shouldn't go to the island, and definitely shouldn't take the book, but I tell her I have no choice, and finally she agrees to meet me at her flat in an hour for me to pick up the book.