The doctors’ surgeries were on a long corridor off the waiting room, and after forty-five minutes had passed since Erlendur had announced his presence a door opened and Dagóbert came out into the waiting area and beckoned to him. Erlendur followed him into his surgery and the doctor closed the door behind them.

‘Has the problem come back?’ Dagóbert asked, inviting Erlendur to lie down on the bed. His file was open on the desk.

‘No,’ Erlendur said. ‘I’m fine. I’m sort of here on official business.’

‘Really?’ the doctor said. He was a fat, humorous man, dressed in a white shirt, a tie and jeans. He might not have worn a white coat but he did have a stethoscope slung round his neck. ‘Won’t you lie down anyway and let me listen to your chest?’

‘No need,’ Erlendur said, taking a chair in front of the desk. Dagóbert sat down on the bed. Erlendur remembered their previous meetings when the doctor had explained how the electrical impulses that controlled his heartbeat had been disrupted. The problem was generally caused by stress. Erlendur understood little of what he had said beyond the fact that the condition was not life-threatening and would get better in time.

‘Then what can I…?’ Dagóbert asked.

‘It’s a medical matter,’ Erlendur said.

He had been struggling with the wording ever since it had first occurred to him to consult the cardiologist. He didn’t want to talk to anyone involved with the police, such as a pathologist, because he didn’t want to have to explain anything.

‘Well, fire away.’

‘If one wanted to kill a person, but only for a couple of minutes, how would one go about it?’ Erlendur asked. ‘If one wanted to revive him immediately so that nobody could see any sign of what had happened?’

The doctor gave him a long look.

‘Do you know of such a case?’ he asked.

‘Actually, I was going to ask you that,’ Erlendur said. ‘I don’t know of any myself.’

‘I’m not aware of anyone having done it deliberately, if that’s what you mean,’ Dagóbert replied.

‘How would one go about it?’

‘That depends on a number of factors. What are the circumstances?’

‘I’m not sure. Let’s say, for example, that it was done at home.’

Dagóbert looked at Erlendur gravely.

‘Has someone you know been messing around with that sort of thing?’ he asked. Dagóbert knew that Erlendur worked for the CID and thought it obvious that his irregular heartbeat was occupational, as he put it. Otherwise he didn’t often slip into jargon, much to Erlendur’s relief.

‘No,’ Erlendur said. ‘And it’s not a police matter. I’m just curious because of an old report I came across.’

‘You’re talking about how to achieve cardiac arrest without its being discovered and in such a way that the victim would survive?’

‘Possibly,’ Erlendur said.

‘Why on earth would anybody want to do something like that?’

‘I have no idea,’ Erlendur replied.

‘I assume you have some further criteria.’

‘Not really.’

‘I don’t quite follow. As I said: why would anyone want to bring about cardiac arrest?’

‘I don’t know,’ Erlendur said. ‘I was hoping you’d be able to tell me.’

‘The first consideration would be the prevention of damage to the organs,’ Dagóbert said. ‘As soon as the heart stops beating, decomposition begins, immediately endangering the tissues and organs. I expect there are a number of drugs that would do the trick by inducing a coma but, from the way you describe it, this might be a case of hypothermia. Otherwise I’m not really sure.’

‘Hypothermia?’

‘Extreme cold,’ the doctor said. ‘It achieves two goals. The heart stops beating when the body temperature drops below a certain level and you experience clinical death, while at the same time the cold has the effect of preserving the body and organs. Cold slows down all metabolic processes.’

‘How would the person be resuscitated?’

‘Probably with a defibrillator, followed by rapid rewarming.’

‘And you’d need specialist knowledge to do that?’

‘Unquestionably. I can’t imagine any other scenario. There would have to be a doctor present, even a cardiologist. And it goes without saying that no one should meddle with this sort of thing.’

‘How long is it possible to keep someone in a state like that before it becomes irreversible?’

‘Well, I’m no expert when it comes to inducing clinical death by hypothermia,’ Dagóbert said, with a smile. ‘But it’s a question of a few short minutes after cardiac arrest – four to five, tops. I don’t know. You’d have to factor in the facilities available to you. If you’re in hospital with access to all the best technology, it might be possible to go even further. Hypothermia has been used in recent years to keep people in a coma while their wounds are healing. It’s also a good method of protecting the organs of people who have experienced cardiac arrest, for example. In that case the body temperature is held at thirty-one degrees Celsius or thereabouts.’

‘If it was done at home, what equipment would you need?’

The doctor stopped and thought.

‘I can’t…’ he began, before breaking off again.

‘What’s the first thing that comes to mind?’

‘A good-sized bathtub. Ice. A defibrillator and easy access to electricity. A blanket.’

‘Would it leave any trace? If the person in question was successfully resuscitated?’

‘Signs that it had taken place? I don’t think so,’ Dagóbert said. ‘I should think it’s like getting caught in a blizzard. The cold gradually slows the metabolic processes; the person would become drowsy initially, then fall into a stupor and finally experience cardiac arrest and death.’

‘Isn’t that exactly what happens when people die of exposure?’ Erlendur asked.

‘Exactly the same.’

The woman who had last spoken to the student Gudrún, as far as could be established with any certainty, now worked as a departmental manager at the National Museum of Iceland. They had been cousins and Gudrún’s parents had asked her to keep an eye on their daughter while they were on their extended trip through Asia. She was three years older than Gudrún, short, with thick blonde hair tied back in a ponytail. Her name was Elísabet and she called herself Beta.

‘I find it very uncomfortable raking this up,’ she said once she and Erlendur had taken a seat in the museum café. ‘I was sort of responsible for Dúna, or at least I felt I was, though of course, you know, I couldn’t have prevented anything. She just vanished. It was absolutely unbelievable. Why are you investigating this now?’

‘We’re closing the file,’ Erlendur said, hoping it would do as an explanation.

‘So you’re sure she’ll never be found now?’ Beta said.

‘It’s been a long time,’ Erlendur said, without answering her directly.

‘I just can’t imagine what could have happened,’ Beta said. ‘One day she drives away and – poof! – she vanishes. Her car’s never found, nor any trace of her. She doesn’t seem to have stopped off at any shops or villages, either on the way north or in the Reykjavík area.’

‘People have mentioned suicide,’ Erlendur said.

‘She just wasn’t the type,’ Beta said immediately.

‘What is the type?’ Erlendur asked.

‘No, I mean, she wasn’t like that.’

‘I don’t know anyone who is,’ Erlendur said.

‘You know what I mean,’ Beta said. ‘And what happened to her car? It can hardly have committed suicide!’

Erlendur smiled.

‘We dragged the harbours all round the country. Sent divers to search along the docks in case she’d lost control of the car. We didn’t find anything.’

‘She was incredibly fond of her little yellow Mini,’ Beta said. ‘I’ve never been able to picture her driving it off some jetty. I’ve always found the idea absurd. Ludicrous.’

‘She didn’t reveal anything about her plans in your last conversation?’

‘Nothing. If I’d known what was going to happen it would have been different. She rang to ask me about a hairdresser’s on Laugavegur I’d recommended to her. She was intending to go there. That’s why I’ve never believed in suicide. There was nothing to point to it.’