“It needn’t be Lothar,” Ilona said. “It could be anyone. You can never tell. You never know who it is. That’s how the system works. That’s how they work.”

He stared at Ilona and knew she was right. Lothar had used him, taken advantage of his anger. What Hannes had written in his message was right. He had said something to someone that should have remained unspoken. No one had warned him. No one had talked about secrets. But he also knew in his heart that no one should have needed to tell him. He felt awful. Consumed by guilt. He was well aware how the system worked. He knew all about interactive surveillance. He had let his rage lead him astray. His naivety had helped them take Hannes.

“Hannes had stopped hanging around with the rest of us Icelanders,” he said.

“Yes,” Ilona said.

“Because he…” He did not finish the sentence.

Ilona nodded.

“What’s going on?” he asked. “What’s really going on here? Ilona?”

She glanced around the group as if waiting for a response. The man who had spoken earlier nodded to her and she revealed that they had contacted her on their own initiative. One member of the group — Ilona pointed to the girl who had greeted him with a handshake — was studying German with her at the university and wanted to know details of what was happening in Hungary, dissent against the communist party there and fear of the Soviet Union. After cautious overtures to probe her views, and once she was convinced that Ilona was in favour of the uprising in Hungary, she asked her to come and meet her companions. The group held clandestine meetings. Surveillance was being stepped up considerably and people were urged increasingly to notify the security police if they became aware of anti-socialist behaviour or attitudes. This was connected with the 1953 uprising and was to some extent a reaction to the situation in Hungary. Ilona had met Hannes at her first meeting with the young activists in Leipzig. They wanted to know about Hungary and whether similar resistance could be built up in East Germany.

“Why was Hannes in this group?” he asked. “How does he come into all this?”

“Hannes was completely brainwashed, just like you,” Ilona said. “You must have strong leadership in Iceland.” She looked towards the man who had spoken before. “Martin and Hannes are friends from engineering,” she said. “It took Martin a long time to get Hannes to understand what we were saying. But we trusted him. We had no reason not to.”

“If you know all this about Lothar, why don’t you do something?” he asked.

“We can’t do anything except avoid him, which is difficult because he’s trained to be friends with everyone,” a man said. “What we can do if he gets too inquisitive is to lead him astray. People don’t cotton on to him. He says what we want to hear and agrees with our views. But he’s false. And he’s dangerous.”

“Wait a minute,” he said, looking at Ilona. “If you knew about Lothar, didn’t Hannes know who he is?”

“Yes, Hannes knew,” Ilona said.

“Why didn’t he say anything? Why didn’t he warn me? Why didn’t he say anything?”

Ilona went up to him.

“He didn’t trust you,” she said. “He didn’t know where you stand.”

“He said he wanted to be left alone.”

“He did want to be left alone. He didn’t want to spy on us or his fellow countrymen.”

“He called after me when I walked out on him. He was going to say something else but he… I was angry, I stormed out. And bumped straight into Lothar.”

He looked at Ilona.

“So that wasn’t a coincidence?”

“I doubt it,” Ilona said. “But it was sure to have happened sooner or later. They were keeping a close watch on Hannes.”

“Are there more people like Lothar at the university?” he asked.

“Yes,” Ilona said. “But we don’t know who they are. We only know about some of them.”

“Lothar is your Betreuer,” said a man sitting in a chair who had been listening to the proceedings without saying a word.

“Yes.”

“What’s your point?” Ilona said to the man.

“Liaisons are supposed to watch the foreigners,” the man said, standing up. “They’re supposed to report everything about the foreigners. We know that Lothar is also meant to get them to collaborate.”

“Tell him what you want to say,” Ilona said and took a step closer to the man.

“How do we know we can trust this friend of yours?”

“I trust him,” Ilona said. “That’s enough.”

“How do you know Lothar is dangerous?” he asked. “Who told you that?”

“That’s our business,” the man said.

“He’s right,” Tomas said, looking towards the man who had doubted his integrity. “Why should you trust me?”

“We trust Ilona,” came the reply.

Ilona smiled awkwardly.

“Hannes said you’d come round eventually,” she said.

He looked at the faded sheet of paper and read the old message from Hannes. Soon it would be evening and the couple would walk past his window. He thought about that night in the basement flat in Leipzig and how it had changed his life. He thought about Ilona and about Hannes and Lothar. And he thought about the terrified people in the basement.

It was the children of those people who had turned Nikolaikirche into their fortress and had rushed out onto the streets when, decades later, the situation finally reached boiling point.

Valgerdur was not with Erlendur at Sigurdur Oli’s barbecue, nor was her name mentioned. Elinborg barbecued delicious loins of lamb which she had marinated in a special spicy sauce with shredded lemon peel, but first they ate a shrimp dish that Bergthora made which Elinborg praised highly. The dessert was a mousse by Elinborg; Erlendur did not catch what was in it but it tasted good. He had never intended to go to the barbecue, but eventually gave in after relentless badgering by Sigurdur Oli and Bergthora. It was not as bad as Elinborg’s book launch, however. Bergthora was so pleased he had come that she allowed him to smoke in the living room. Sigurdur Oli’s face fell a mile when she brought him an ashtray. Erlendur watched him with a smile and felt he had earned his reward.

They did not discuss work, apart from one occasion when Sigurdur Oli began wondering why the Russian equipment had been kaput before it went into the lake with the body. Erlendur had told them about the forensics results. The three of them were standing together on the patio. Elinborg was preparing the grill.

“Doesn’t that tell us something?” she asked.

“I don’t know,” Erlendur said. “I don’t know whether it matters whether it worked or not. I can’t see the difference. A listening device is a listening device. Russians are Russians.”

“Yes, I guess so,” Sigurdur Oli said. “Maybe it was damaged in a struggle. Fell to the floor and smashed.”

“Conceivably,” Erlendur said. He looked up at the sun. He did not really know what he was doing out there on the terrace. He had not been to Sigurdur Oli and Bergthora’s house before even though they had worked together for a long time. It did not surprise him to find everything neat and tidy there: designer furniture, objets d’art and smart flooring. Not a speck of dust to be seen. Nor any books.

Indoors, Erlendur perked up when he learned that Teddi, Elinborg’s husband, knew about Ford Falcons. Teddi was a chubby car mechanic who was in love with Elinborg’s cooking, like most people who knew her. His father had once owned a Falcon and he was a great admirer of the model. Teddi told Erlendur that it had been very smooth to drive, with a bench for the front seat, automatic gearbox and a big ivory steering wheel. It was a smaller family car than other American models from the 1960s, which tended to be huge.

“It didn’t do too well on the old Icelandic roads,” Teddi said as he scrounged a cigarette from Erlendur. “Maybe it wasn’t built strongly enough for Icelandic conditions. We had a lot of bother when the axle broke once out in the countryside. Dad had to get a lorry to transport it back to town. They weren’t particularly powerful cars, but good for small families.”