The couple looked at each other.

“Make too much fuss about it?” she said, surprised. “We’re not making any fuss about it. Do you think we’re making any fuss about it, Eyvi?” She looked at her husband, who seemed unaware how to answer. “Go on, answer me!” she said sharply and he gave a start.

“No, I wouldn’t say that, that’s not right.”

Sigurdur Oli’s mobile phone rang. He didn’t keep it loose in his pocket like Erlendur, but in a smart holder attached to the belt around his stiffly pressed trousers. Sigurdur Oli asked the couple to excuse him, stood up and answered the phone. It was Erlendur.

“Can you meet me at Holberg’s flat?” he asked.

“What’s going on?” Sigurdur Oli said.

“More digging,” Erlendur said and rang off.

When Sigurdur Oli drove into Nordurmyri, Erlendur and Elinborg were already there. Erlendur was standing in the doorway to the basement smoking a cigarette. Elinborg was inside the flat. As far as Sigurdur Oli could see she was having a good sniff around, she stuck her head out and sniffed, exhaled and then tried somewhere else. He looked at Erlendur who shrugged and threw his cigarette into the garden and they went inside the flat together.

“What kind of smell do you think there is in here?” Erlendur asked Sigurdur Oli, and Sigurdur Oli started sniffing at the air like Elinborg. They walked from room to room with their noses in the air, except Erlendur who had a particularly poor sense of smell after so many years of smoking.

“When I first came in here,” Elinborg said, “I thought that horsey people must live in the building or in this flat. The smell reminded me of horses, riding boots, saddles, or that sort of thing. Horse dung. Stables, really. It was the same smell that was in the first flat my husband and I bought. But there weren’t any horse-lovers living there either. It was a combination of filth and rising damp. The radiators had been leaking onto the carpet and parquet for years and no-one had done anything about it. We also had the spare bathroom converted but the plumbers did it so badly, just stuffed straw into the hole and put a thin layer of concrete over it. So there was always a smell of sewers that came up through the repair.”

“Which means?” Erlendur said.

“I think it’s the same smell, except it’s worse here. Rising damp and filth and sewer rats.”

“I had a meeting with Marion Briem,” Erlendur said, uncertain whether they knew the name. “Naturally Marion read up on Nordurmyri and reached the conclusion that the fact it’s a marsh is important.”

Elinborg and Sigurdur Oli exchanged glances.

“Nordurmyri used to be like a distinct village in the middle of Reykjavik,” Erlendur went on. “The houses were built during or just after the war. Iceland had become a republic and they named the streets after the saga heroes, Gunnarsbraut, Skeggjagata and all that. It was a wide cross-section of society who gathered here, ranging from the reasonably well-off, even the rich, to those who barely had a penny to their name so they rented cheap basement flats like this one. A lot of old people like Holberg live in Nordurmyri, though most of them are more civilised than he was, and many of them live in precisely this type of basement flat. Marion told me all this.”

Erlendur paused.

“Another feature of Nordurmyri is this sort of basement flat. Originally there weren’t any basement flats, the owners had them converted, installed kitchens and walls, made rooms, made places to live. Previously these basements were where the work was done for, what did Marion call them? Self-contained homes. Do you know what that is?”

They both shook their heads.

“You’re too young, of course,” Erlendur said, well aware that they would hate him saying that. “In basements like this were the girls’ rooms. They were maids in the homes of the more wealthy people. They had rooms in holes like this. There was a laundry room too, a room for making haggis, for example, and other food, storerooms, a bathroom and all that.”

“Not forgetting that it’s a marsh.” Sigurdur Oli said sarcastically.

“Are you trying to tell us something important?” Elinborg said.

“Under these basements are foundations…” Erlendur said.

“That’s quite unusual,” Sigurdur Oli said to Elinborg.

“… just like under all other houses,” Erlendur continued, not letting Sigurdur Oli’s quips disturb him. “If you talk to a plumber, as Marion Briem did…”

“What’s all this Marion Briem bullshit anyway?” Sigurdur Oli said.

“… you’ll find out they’ve often been called out to Nordurmyri to deal with a problem that can arise years, decades after houses have been built on marsh land. It happens in some places but not others. You can see it happening on the outside of some houses. A lot of them are coated with pebbledash and you can see where the pebbledash ends and the bare wall of the house starts at ground level. A strip of maybe one or two feet. The point is that the ground subsides indoors too.”

Erlendur noticed they’d stopped grinning.

“In the estate-agency business it’s called a concealed fault and it’s difficult to know how to deal with this sort of thing. When the houses subside it puts pressure on the sewage pipes and they burst under the floor. Before you know it, you’re flushing your toilet straight into the foundations. It can go on for ages because the smell can’t get through the concrete. But damp patches form because the hot-water outflow in many old houses is connected into the sewage pipe and leaks into the basement when the pipe breaks, it gets hot and the steam reaches the surface. The parquet warps.”

Erlendur had their complete attention by now.

“And Marion told you all that?” Sigurdur Oli said.

“To fix it you have to break up the floor,” Erlendur continued, “and go down into the foundations to mend the pipe. The plumbers told Marion that sometimes when they drilled through the floor they’d hit a hollow. The base plate is fairly thin in some places and underneath there’s an air pocket. The ground has subsided by half a yard, maybe even a whole yard. All because of the marsh.”

Sigurdur Oli and Elinborg looked at each other.

“So is it hollow under the floor here?” Elinborg asked, stamping with one foot.

Erlendur smiled.

“Marion even managed to locate a plumber who came to this house the same year as the national festival. Everyone remembers that year and this plumber clearly recalled coming here because of the damp in the floor.”

“What are you trying to tell us?” Sigurdur Oli asked.

“The plumber broke up the floor in here. The base plate isn’t very thick. It’s hollow underneath in a lot of places. The plumber remembers the job so clearly because he was shocked that Holberg wouldn’t let him finish.”

“How come?”

“He opened up the floor and mended the pipe, then Holberg threw him out and said he’d finish it himself. And he did.”

They stood in silence until Sigurdur Oli couldn’t resist the temptation any longer.

“Marion Briem?” he said. “Marion Briem!” He said the name over and again as if struggling to understand it. Erlendur was right. He was too young to remember Marion from the force. He repeated the name like it was some kind of conundrum, then suddenly stopped and looked thoughtful and finally asked:

“Wait a minute. Who is this Marion? What kind of name is that anyway? Is it a man or a woman?”

Sigurdur Oli gave Erlendur a questioning look.

“I sometimes wonder myself,” Erlendur replied and took out his mobile phone.