'Don't worry, I don't want to talk to you about Agnar,' Magnus began.

'Good,' said Tomas.

'It's another murder I want to discuss with you. One that took place seventeen years ago.'

Tomas was suddenly awake, his eyes focusing on Magnus.

'Know whose murder I'm talking about?'

Tomas remained motionless. Magnus felt that he wasn't trusting himself to speak. A good sign.

'That's right,' he said. 'Dr asgrimur. Seventeen years ago your father pushed Dr asgrimur off a cliff. And you witnessed it.'

Tomas swallowed. 'I don't know what you are talking about.'

'I've just come back from Hruni where I interviewed your father. And I went to alfabrekka and spoke to the farmers who helped him go back and find Dr asgrimur. They saw you.'

'They can't have done.'

'They saw a thirteen-year-old boy sneak by their farm in the snow.'

Tomas frowned. 'That wasn't me.'

'Wasn't it?'

'Anyway. Why would my father kill the doctor? They were friends.'

Magnus smiled. 'The ring.'

'What ring?'

'The ring you went to talk to Professor Agnar about.'

'I have no idea what you are talking about.'

Magnus leaned forward. He spoke in a low urgent voice, only a fraction above a whisper. 'You see, the farmers saw your father wearing an ancient ring. We know that your father pushed Dr asgrimur off a cliff and took the ring. You witnessed it and ran away.'

'Has he admitted it?' Tomas asked.

Magnus could see that the instant he had uttered it, Tomas regretted his question, with its implication that there was something to admit.

'He will. We are going to arrest him shortly.'

He paused, watching Tomas as he fiddled with the empty coffee cup in front of him. 'Tell us the truth, Tomas. You can stop protecting your father. It's too late for that.'

Tomas glanced at his lawyer, who was listening intently. 'OK.'

'Talk to me,' said Magnus.

Tomas took a deep breath. 'I wasn't there,' he said. 'I don't know who your farmer witness saw, but it wasn't me.'

Magnus was tempted to argue, but held his tongue. Best to coax out the entirety of Tomas's story and then pick holes in it.

'I don't even know for sure whether my father did kill him, I really don't. But I do know that he has the ring, Gaukur's ring.'

'How do you know?' Magnus asked.

'He told me. About five years later, when I was eighteen or so. He said that he was looking after it for me. He told me the whole story of the ring, how it was the very same ring of Andvari from the Volsung Saga, about how isildur had taken it back to Iceland and how Gaukur had killed his brother for it, and had then hidden it. He showed it to me once.'

'So you've actually seen it?'

'Yes.'

'Did he tell you how he got it?'

Tomas hesitated. 'Yes. Yes, he did. He said that he and Dr asgrimur found it that weekend, and that Dr asgrimur was wearing it when he fell off the cliff. He said that he had taken it off Dr asgrimur's finger.'

'While he was lying dying at the bottom of the cliff?'

Tomas shrugged. 'I guess so. I don't know. It was either then, or when he came back for him with the farmers and found him dead. But it would have been quite difficult to take the ring then, I would expect.'

'Didn't that shock you?'

'Yes, it did.' Tomas swallowed. 'My father was always a bit strange. But he became much stranger after the doctor died. I was scared of him, in awe of him. I still am, if the truth be told. And, well ...'

'Yes?'

'Well, I wouldn't be surprised if he had done something awful like take a ring off a dying man's finger.'

'What about killing that man?'

Tomas hesitated. Magnus glanced at Tomas's lawyer. She was listening intently, but letting him speak. As far as she was concerned her client was going some way towards exonerating himself.

Baldur was also listening closely, letting Magnus get on with it.

Tomas took a deep breath. 'Yes. Like killing the doctor.'

'Did he admit he had done that?'

'No, not at all. Never.'

'But you suspect he did?'

'Not at first,' said Tomas. 'It didn't occur to me. I had always believed my father about everything. But then the suspicion did begin to nag at me. I hoped it wasn't true, but I couldn't help asking myself, what if Father had pushed the doctor?'

'Did you confront him?'

'No, absolutely not.' It was clear that the last thing on earth Tomas would do was confront his father. 'But one day I overheard something. It was Father talking to my mother, this was several years after they had separated. It was Birna asgrimsdottir's wedding. Father was officiating. They were talking about how messed up Birna was. Father said something like: "It's hardly surprising when her father was murdered."

'I don't know whether Mother noticed. She didn't say anything. I could tell Father had realized he had made a mistake by the way he glanced at her immediately. I don't think he knew I was listening.'

'That's not exactly hard evidence,' Magnus said.

'No,' Tomas admitted.

Which was no doubt why Tomas had told them. Magnus still wasn't convinced that Tomas wasn't there and hadn't witnessed the whole thing. But he'd come to that later.

'All right. So why were you visiting Agnar?'

'Can I have some water?' Tomas asked.

Magnus nodded. To Magnus's surprise Baldur went to the door to ask for some. A minute later a police officer returned with a plastic cup and a jug.

Tomas drank gratefully. Gathering his thoughts.

'Agnar approached me. We knew each other vaguely, we'd met at parties, had one or two mutual friends, you know how this town is?'

Magnus nodded.

'We met at a cafe.'

'Cafe Paris,' Magnus said, remembering his conversation with Katrin, about her seeing them together.

Tomas frowned in surprise.

'Go on,' Magnus said.

'Agnar said that he had been approached by a wealthy American to buy Gaukur's ring. I acted dumb, but Agnar went on. He said that he had just come back from Hruni, where he had spoken to Father. He said that although Father denied he had the ring, Agnar was sure he was lying.'

'Did he say why?'

'He did. It was ridiculous.' Tomas smiled to himself. 'He said it was because Father looked much younger than his age. In Gaukur's Saga the warrior who bears the ring, Ulf something, is actually ninety, but looks much younger, and Agnar's theory was that the same thing was happening to Father, he wasn't getting any older.'

'I see what you mean,' said Magnus. 'That is a little weird.'

'I know. The problem was I laughed at him. It was a problem because right then Agnar could tell I knew what he was talking about.'

'But you didn't actually admit it?'

'No. Then he claimed that Father must have murdered Dr asgrimur. Obviously, I said that was wrong. But Agnar persisted. He seemed very sure of himself. Basically, he tried to blackmail me. Or us.'

'How?'

'He said that unless Father sold him the ring and Agnar promised he would pay a high price then he would go to the police and tell them, I mean you, about the ring and about Dr asgrimur's murder.'

'So what did you do?'

'I called Father. I told him what Agnar had said.'

'How did he take it?'

'He wasn't having any of it. We agreed how absurd it was that Agnar should think that Father had murdered Dr asgrimur. But, of course, Father knew I knew he had the ring. He said we should call Agnar's bluff. So I went to look for him. I went to the University first, and then a student said he was at a summer house on Lake Thingvellir. I actually knew the house, I interviewed Agnar's father there a few years ago. You know he was a cabinet minister?'

Magnus nodded.

'So I drove out to Lake Thingvellir. I told Agnar that my father had no idea what he was talking about. I urged him to drop the blackmailing.'

'Urged?' said Magnus. 'Or threatened.'

'Urged. I pointed out that if Agnar went through with it, his clients almost certainly wouldn't get the ring. I kind of admitted I knew that Father had it.'

'What did Agnar say?'

'He looked at me for several seconds, thinking. Then he suggested that if Father was too stubborn to give up the ring of his own accord, I should steal it from him. That way I would keep him out of jail.'

'What did you say?'

'I said I would think about it.'

Magnus raised his eyebrows.

'Agnar had a point. I knew Father would never give up the ring, but I didn't want him to go to jail. I knew where Father kept it, and it would be easy to take it and sell it to Agnar.'

'So did you?'

'Steal the ring? No. I drove straight home, and sat down and thought about it. In the end I decided to tell Father what Agnar had suggested. I called him that evening.'

'And what did your father say?'

'He was angry. Very angry.'

'With you?'

'With Agnar and with me. He was upset that I had as good as admitted that he had the ring. He didn't seem at all grateful that I had stood by him, that I had called him instead of taking the ring myself.' There was anger in Tomas's voice. 'He lost it, basically.'

'So what did you do?'

'I was wound up. I had a drink or two to calm myself down.' Tomas winced. 'I ended up drinking most of a bottle of whisky. I woke up late the next morning, still not sure what to do. Then I heard about Agnar's death on the radio.'

Tomas swallowed.

'What's the timing on all this?' Magnus asked. 'When did you get home from Lake Thingvellir?'

'About half-past five or so. Like I told your colleague.' Tomas's eyes flicked towards Baldur.

'And what time did you call your father?'

'About half an hour later, maybe an hour.'