“Maybe you still don’t today,” Sigurdur Oli said.

“We had a look in our archives,” Quinn said, no longer smiling. “Bob remembered it well. Everyone thought it was a mystery at the time and what was actually going on was never uncovered. What happened, according to our records — and I’ve talked to Bob in detail about this as well — is that an East German attache entered Iceland at a certain time but we never noticed him leaving again.”

They looked at him blankly.

“Perhaps you’d like me to repeat that,” Quinn said. “An East German diplomat came to Iceland but did not leave. According to our information, which is fairly reliable, either he’s still here — and doing something completely different from embassy work — or he was killed and the body either disposed of or sent out of the country.”

“So you lost him in Iceland?” Elinborg said.

“It’s the only case of this sort that we know about,” Quinn said. “In Iceland, that is,” he added. “The man was an East German spy. He was known to us as such. None of our embassies in other parts of the world picked him up after he came to Iceland. A special alert was sent out about him. He never appeared. We made a special check on whether he had returned to East Germany. It was like the earth had swallowed him. The Icelandic earth.”

Elinborg and Sigurdur Oli mulled over his words.

“Could he have gone over to the enemy — I mean to you, the British or the French?” Sigurdur Oli said, trying to recall films and books about spies that he had seen and read. “And then gone underground?” he added, unsure of exactly what he was talking about. He was not a great fan of spy stories.

“Out of the question,” Quinn said. “We would have known about that.”

“Or used a false identity when he left the country?” Elinborg suggested, groping and as much in the dark as Sigurdur Oli.

“We knew most of them,” Quinn said. “And we kept a fairly good watch on their embassies on that score. We believe that this man never left the country.”

“What about in some other way from what you expected?” Sigurdur Oli said. “By ship?”

“That was one possibility we checked,” Quinn said. “And without going into too much detail about our procedures then and now, I can assure you that this man never emerged in East Germany, which was where he came from originally, nor in the Soviet Union or any other country in Eastern or Western Europe. He vanished.”

“What do you think happened? Or thought at the time?”

“That they killed him and buried him in the embassy garden,” Quinn said without batting an eyelid. “Killed their own spy. Or, as has since transpired, sank him in Lake Kleifarvatn tied to one of their listening devices. I don’t know why. It’s perfectly clear that he didn’t work for us, nor for any NATO country. He wasn’t a counter-espionage agent. If he was, he was working so deep that nobody knew about it, and he would probably have hardly known it himself.”

Quinn flicked through the folder and told them that the man had first come to Iceland in the early 1960s and worked in the diplomatic corps for a few months. Then, in autumn 1962, he left, but returned briefly two years later. After that he had moved between posts in Norway, East Germany and Moscow for one year and ended up at the East German embassy in Argentina, with the title of “trade attache” — “like most of them,” Quinn said, grinning. “Our guys too. He spent a short spell at the embassy in Reykjavik in 1967, then went back to Germany and from there to Moscow. He returned to Iceland in 1968, in the spring. By the fall he had disappeared.”

“Fall 1968?” Elinborg said.

“That was when we noticed that he was no longer at the embassy. We investigated through specific channels and he was nowhere to be found. Admittedly, the East Germans did not operate a proper embassy in Reykjavik, only what was called a trade delegation, but that’s a minor point.”

“What do you know about this man?” Sigurdur Oli asked. “Did he have friends here? Or enemies at home? Did he do anything wrong to your knowledge?”

“No. As I say, we’re not aware of that. And of course we don’t know everything. We suspect that something happened to him here in 1968. We don’t know what. He could just as easily have left the diplomatic service and made himself disappear. He knew how to do that, how to merge into the crowd. It’s up to you how you interpret this information. This is all we know.”

He paused.

“Perhaps he slipped away from us,” he said then. “Maybe there’s a rational explanation for it all. This is all we’ve got. Now you must tell me one thing. Bob asked about it. How was he killed? The man in the lake.”

Elinborg and Sigurdur Oli exchanged glances.

“He was hit over the head and sustained a hole in the skull just by the temple,” Sigurdur Oli said.

“Hit over the head?” Quinn asked.

“He could have fallen, but it would have been from quite a height,” Elinborg said.

“So it’s not a straightforward execution? A bullet in the back of the head?”

“Execution?” Elinborg said. “We’re Icelanders. The last execution in this country was done with an axe almost two hundred years ago.”

“Yes, of course,” Quinn said. “I’m not saying that an Icelander killed him.”

“Does it tell you anything, him dying like that?” Sigurdur Oli asked. “If it is this spy who was found in the lake?”

“No, nothing,” Quinn said. “The man was a spy and his job entailed certain risks.”

He stood up. They could tell that the conversation was coming to an end. Quinn put the folder down on the table. Sigurdur Oli looked at Elinborg.

“What was his name?”

“His name was Lothar,” Quinn said.

“Lothar,” Elinborg parroted.

“Yes,” Quinn said, looking at the papers he was holding. “His name was Lothar Weiser and he was born in Bonn. And, interestingly enough, he spoke Icelandic like a native.”

Later that day they requested a meeting at the German embassy, stating the reason to give the staff time to gather information about Lothar Weiser. The meeting was arranged for later in the week. They told Erlendur about what the meeting with Patrick Quinn had revealed, and discussed the possibility that the man in the lake was an East German spy. A number of signs pointed to that, they felt, notably the Russian device and the location. They agreed that there was something foreign about the murder. Something about the case that they had seldom, if ever, seen before. Admittedly it was ferocious, but all murders were ferocious. More importantly, it appeared to have been carefully planned, skilfully executed, and had remained covered up for so many years. Icelandic murders were not generally committed in this way. They were more coincidental, clumsy and squalid, and the perpetrators almost without exception left a trail of clues.

“If he didn’t just fall on his head,” Elinborg said.

“No one falls on their head before being tied to a spying device and thrown into Kleifarvatn,” Erlendur said.

“Making any progress with the Falcon?” Elinborg asked.

“None at all,” Erlendur said, “except that I’ve been putting the wind up Leopold’s girlfriend, who can’t understand what I’m going on about.” Erlendur had told them about the brothers from outside Mosfellsbaer and his half-baked hypothesis that the man who owned the Falcon might even still be alive or, for that matter, living in another part of Iceland. They had discussed this idea before and regarded it in much the same way as the missing man’s girlfriend — they had nothing substantial to support it. “Too far-fetched for Iceland,” Sigurdur Oli said. Elinborg agreed. “Perhaps in a city of a million people.”

“Funny that this guy can’t be found anywhere in the system, though,” Sigurdur Oli said.

“That’s the point,” Erlendur said. “Leopold, as he called himself — that much we do know — is quite a mysterious figure. Niels handled the case originally and never looked into his background properly, he never found any records. It wasn’t investigated as a criminal matter.”