Sigmund nodded.

'That door should just be closed,' said Adam. 'Along with several other doors that are just creating draughts and chaos with all their possibilities. These poison-pen letters, for example. Have you ever been involved in a case where the murderer was one of the people who'd sent that sort of thing?'

'Well,' Sigmund said hesitantly. 'In the Anna Lindh case the murderer was unhappy about-'

'The Swedish Minister for Foreign Affairs was murdered by a madman,' Adam interrupted. 'In every practical respect, if not in the legal sense. A misfit with a psychiatric background who suddenly caught sight of a focus for his hatred. He was arrested two weeks later, and he left so many clues that-'

'That you and I would have picked him up in less than twenty-four hours,' Sigmund smiled.

Adam grinned back.

'They've been really unlucky, the Swedes, in several really, really serious cases ...'

Once again they fell silent. From the room next door came the sound of a running shower and a toilet being flushed.

'I think that's a blind alley, too,' said Adam. 'Just like this abortion business the papers are making so much of at the moment. It's the anti-abortion lobby that sometimes commits murders in support of their point of view. In the US, anyway. Not the pro-abortionists. That's just too far-fetched.'

'So what are you thinking, then? You've gone through virtually every possibility we've got! What the h.e.l.l are you sitting there pondering?'

'Where was she going?' said Adam, staring blankly into s.p.a.ce. 'We have to find out where she was going when she was murdered.'

Sigmund emptied his gla.s.s and stared at it briefly before resolutely opening the plastic bottle of Famous Grouse and pouring himself another decent measure.

'Take it easy,' said Adam. 'We've got to make an early start.'

Sigmund ignored his warning.

'The problem is, of course, that we can't ask Eva Karin Lysgaard,' he said. 'And her husband is still flatly refusing to say anything about where she was heading. Our colleagues here have told him he has a duty to answer, and have even threatened him with a formal interrogation. With the consequences that could have-'

'They'll never subject Erik Lysgaard to a formal interrogation. It would be pointless. He has suffered enough and is still suffering. We'll have to come up with something else.'

'Like what?'

Adam emptied his gla.s.s and shook his head when Sigmund lifted the bottle to offer him a top-up.

'Door-to-door enquiries,' Adam said tersely.

'Where? All over Bergen?'

'No. We need to ...' He opened the drawer of the bedside table and took out a map of the town. 'We need to concentrate on a limited area somewhere around here,' he said, drawing a circle with his index finger as he held the map up to show his colleague.

'But that's half of b.l.o.o.d.y Bergen,' Sigmund said wearily.

'No. It's the eastern part of the centre. The north-eastern part.'

Sigmund took the map.

'You know what, Adam? This is the stupidest suggestion you've ever come up with. It's been made absolutely crystal-clear in the media that there's a great deal of uncertainty about why the Bishop was out walking on Christmas Eve. If anyone out there knew where she was going, they would have contacted the police long ago. Unless, of course, they have something to hide, in which case there's still no b.l.o.o.d.y point in going around knocking on doors.'

He threw the map on the bed and took a large swig from his gla.s.s.

'Besides,' he went on, 'she might just have gone out for a walk. In which case we wouldn't be any closer to finding an answer.'

Adam's face took on the gla.s.sy expression Sigmund knew so well.

'Any more bright ideas?' he said, sipping his whisky. 'Ideas I can shoot down right now?'

'The photo,' said Adam firmly, before glancing at his watch.

'The photo. Right. What photo?'

'It's half past eleven. I need to get some sleep.'

'Which photo are you talking about?'

Sigmund showed no sign of heading off to his own room. On the contrary, he settled himself more comfortably in the armchair and rested his legs on the bed.

'The one that disappeared,' said Adam. 'I told you about the photograph that was in the "spare room" ...'

He drew quotation marks in the air.

'... where Eva Karin used to go when she couldn't sleep, according to the family. There were four photographs in there the first time I saw the room, and three when I went back two days later. The only thing I remember is that it was a portrait.'

'But Erik Lysgaard doesn't want to-'

'We'll just have to forget Erik. He's a lost cause. I've spent far too long thinking the key to finding out more about this mysterious walk lies with him. But we've reached stalemate there. Lukas, however-'

'Doesn't seem all that keen to cooperate either, if you ask me.'

'No, you could be right there. Which means we have to ask ourselves why a son who is obviously grieving and who really wants to find out who murdered his mother is so reluctant to help the police. There's usually only one explanation for that kind of thing.'

He looked at Sigmund with raised eyebrows, challenging him to follow his reasoning through to its conclusion.

'Family secrets,' said Sigmund in a dramatic tone of voice.

'Bingo. They often have nothing to do with the matter in hand, actually, but in this case we can't afford to make any a.s.sumptions. My impression of Lukas is that he's not really ...'

There was a long pause. Sigmund waited patiently; his gla.s.s wasn't empty yet.

'... he's not really sure of his father,' Adam said eventually.

'What do you mean?'

'They're obviously very fond of each other. There's a striking resemblance between them, both physically and in terms of personality, and I have no reason to believe there's any problem with the relationship between father and son. And yet there's something unresolved between them. Something new. You notice it as soon as you're in the same room with both of them. It's a long way from hostility, it's more a kind of ...'

Once again he had to search for the right words.

'... broken trust.'

'Do they suspect each other?'

'I don't think so. But there's something unspoken between them, some kind of deep scepticism that ...'

Once again, mostly as a reflex action, he looked at his watch.

'I mean it, Sigmund. I have to get to sleep. Clear off.'

'You always have to spoil the party,' mumbled his colleague, putting his feet on the floor. His room was two doors away, and he couldn't be bothered with his shoes. He picked them up with two fingers of his right hand, and carried the whisky bottle in the other.

'What time are you having breakfast?'

'Seven. Then I'm going out to Os. I want to catch Lukas before he goes to work. That's what we have to hope for that Lukas will agree to help us.'

He yawned and weakly raised two fingers to his forehead in a farewell salute. In the doorway Sigmund turned back.

'I think I'll get up a bit later,' he said. 'Then I'll go straight down to the police station about nine. I'll let them know you've gone to talk to Lukas again. They seem to think it's OK for you to go off on your own here in Bergen. You'd never get away with it back home!'

'Fine. Good night.'

Sigmund mumbled something inaudible as the door closed behind him with a muted bang.

As Adam undressed and got ready for bed, he realized he'd forgotten to ring Johanne. He swore and looked at his watch, even though it was only two minutes since he'd established that it was eleven thirty-six.

It was too late to call, so he went to bed.

And couldn't get to sleep.

It was the number 19 that was keeping Johanne awake. She had spent the entire evening reading about Rashad Khalifa and his theories about the divine origins of the Koran. Whatever she tried to think about in order to tempt sleep, that d.a.m.ned number 19 popped up again, and she was wide awake once more.

After an hour she gave up. She would find something mindless to watch on TV. A detective programme or a sitcom; something to make her sleepy. It was already after one o'clock, but TV3 was usually showing some kind of c.r.a.p at this time of night.

The sofa was a complete mess. Papers everywhere, every single one a printout from the Internet.

Johanne threatened her own students with death and destruction if they ever used Wikipedia as a source in a piece of academic work. She used it all the time. The difference between Johanne and her students was that she had the sense to be critical, in her opinion. This evening it had been difficult. The story of Rashad Khalifa made riveting reading, and every link had led her deeper into this remarkable story.

It was so fascinating.

She padded silently into the kitchen and decided to follow her mother's advice. Milk in a pan, two large dessert spoonfuls of honey. Just before it boiled she added a dash of brandy. As a child she hadn't had a clue about the final ingredient. As an adult she had confronted her mother, telling her it was totally irresponsible to give a child alcohol to get her to sleep. Her mother had waved away her objections, pointing out that the alcohol evaporated, and that in any case alcohol could be regarded as medicine. At least in these circ.u.mstances. Besides which they were very rarely given her special milk mixture, she had added, when Johanne still didn't seem convinced.

She smiled and shook her head at the thought. Poured the milk into a big mug. It was almost too hot to hold.

She put it down on the coffee table and made some s.p.a.ce on the sofa. Switched on the TV and flicked on to TV3. It was difficult to work out what the film was actually about. The pictures were dark, showing trees being blown down in a violent storm. When a vampire suddenly appeared among the tree trunks, she switched off.

Without really making a conscious decision, she reached for a pile of papers next to her mug of milk. Despite the fact that it was a stupid thing to do in view of the late hour, she settled down to read more about Rashad Khalifa and his peculiar theory about the number 19.

The Egyptian had emigrated to the United States as a young adult, and trained there as a biochemist. Since he found the English translation of the Koran unsatisfactory, he re-translated the whole thing himself. During the course of his work, towards the end of the Sixties, he got the idea that the book ought to be a.n.a.lyzed. From a purely mathematical point of view. The aim would be to prove that the Koran was a divine text. After several years and a great deal of work, he put forward his theory about the number 19 as a kind of pervading, divine key to the word of Allah.

Johanne didn't have the requisite knowledge to follow the strange Muslim's great leaps of thought. The whole thing seemed to be based on comparatively advanced mathematics, while in some parts it seemed utterly ba.n.a.l. For example, he noted that in the Koran, 'Basmalah' is mentioned 114 times, which is a number divisible by 19. In certain places he based his comments more directly on the text, such as when he referred to the fact that sura 74:30 said, 'Over it is nineteen.'

Tentatively, she took a sip of the hot milky drink. Her mother's theory didn't stand up; the alcohol burned on her tongue and p.r.i.c.kled in her nose.

Rashad Khalifa carried out an inconceivable number of calculations, she noted once more. The most ridiculous was to add up all the numbers mentioned throughout the whole of the Koran, and to show that this total was also divisible by 19. At first she really couldn't understand what was special about that, but then she realized that 19 was a prime number, and therefore divisible only by itself, and that made things slightly easier to understand.

'But then there are a h.e.l.l of a lot of prime numbers,' she muttered to herself.

The room was cold.

They had installed a thermostat with a timer on every radiator in an attempt to protect both their bank account and the environment. While Adam kept on turning up the radiators to maintain the heat overnight, she kept turning them down to allow the system to work as it was meant to. She regretted it now. For a moment she considered lighting a fire, but instead she went into the bedroom and fetched a blanket.

Her drink was beginning to cool down. She took a big gulp, then put the mug down again and started to read.

To begin with, the Muslim world had seemed delighted with the eccentric Khalifa's discoveries. At first his work was taken seriously. Muslims the world over accepted the idea of mathematical evidence for the existence of Allah. Even the well-known sceptic Martin Gardner referred to Khalifa's mathematical discoveries as interesting and sensational in one of his articles in Scientific American.

Then things went downhill for the Egyptian-American Rashad Khalifa.

He wrote himself into the Koran.

Not content with regarding himself as a prophet on the same level as the Prophet, he created his own religion. According to 'The Submitters', all other religions, including corrupt Islam, would simply die out when the prophet foretold in both the Koran and the Bible arrived, and Islam would rise again in a pure, unadulterated form.

She was going cross-eyed. Johanne put down the papers.

Perhaps she would be able to sleep on the sofa.

She wasn't going to think about Rashad Khalifa any more.

Still, it was hardly surprising that he gained supporters, she thought, trying to get comfortable. Many modern Muslims welcomed his attack on the Muslim priesthood. On the other hand, numerology would always tempt those with a weakness for fanaticism extremists of all kinds. Khalifa's theories were still accepted, in spite of the fact that the man himself had been murdered in 1990.

By a fanatical Muslim, following a fatwa issued at the same meeting as the one against Salman Rushdie.

'Oh my G.o.d,' she mumbled, trying to close her eyes. 'These religions!'

The number 19 was performing Riverdance on the inside of her eyelids.

It was ten past two.

Tomorrow would be terrible if she didn't get to sleep soon. She got up abruptly, and with the blanket tucked under her arm she padded into the bathroom to take a sleeping tablet. The very thought that they were there was usually enough, but this time she took one and a half tablets, swilled down with running water from the tap.

Fifteen minutes later she was fast asleep in her own bed, untroubled by dreams.

Lukas Lysgaard had waited until everyone was asleep. He left a note for Astrid saying that he was worried about his father and was going to check that everything was OK, but would be back later that night. He had left the car parked on the street so that the garage door wouldn't wake anyone.

The drive did him good. While his mother had always adored the light, Lukas was a man who felt comfortable at night. As a child he had always felt safe in the dark. The night was his friend, and had been ever since he was little and lived in the big house on Nubbebakken. From the age of six or seven he had often woken up and been fascinated by the shadows dancing on his bedroom wall. The big oak tree whose branches sc.r.a.ped against the window pane was illuminated from behind by a single yellow street lamp, making the most beautiful patterns on his bed. All of a sudden, when he could no longer sleep, he would tiptoe out of his room and up the steep stairs leading to the attic. In the semi-darkness, among trunks and old furniture, moth-eaten clothes and toys that were so old n.o.body knew who had owned them originally, he could sit for hours, lost in dreams.

Lukas Lysgaard drove from Os through the damp winter darkness into a Bergen that was heavy with sleep; he had finally made a decision.