Mikkelina scuttled away from the doorway to the dark passage. Tomas stayed there watching Grimur, who smiled at him.

“But me and Tomas are friends,” Grimur said.

“Tomas would never betray his dad. Come here, son. Come to Daddy.”

Tomas went up to him.

“Mum phoned,” he said.

“Tomas!” their mother shouted.

“I don’t think Tomas intended to help him. It’s more likely that he thought he was helping Mum. Perhaps he wanted to scare him to do her a favour. But I think it’s most likely he didn’t know what he was doing. He was so small, the dear child.”

Mikkelina looked at Erlendur. He and Elinborg were in her sitting room and had listened to her account of the mother from the hill and Grimur, how they met and the first time he hit her, how the violence gradually intensified and twice she tried to flee from him, how he threatened to kill her children. She told them about life on the hill, the soldiers, the depot, the thefts and the soldier called Dave who went fishing in the lake, and about the summer their father was imprisoned and her mother and the soldier fell in love, how her brothers carried Mikkelina out into the sunshine, how Dave took them for picnics, and about the cold autumn morning when her stepfather returned.

Mikkelina took all the time she needed to tell her story, and tried not to omit any part of the family’s history that she thought might be relevant. Erlendur and Elinborg sat and listened, drinking the coffee Mikkelina had made for them and eating the cake she had baked because, she said, she knew Erlendur would be coming. She greeted Elinborg sincerely and asked if there were many women detectives.

“Next to none,” Elinborg smiled.

“Sinful,” said Mikkelina, offering her a seat. “Women should be in the forefront everywhere.”

Elinborg looked at Erlendur, who gave a half smile. She had picked him up from the office in the afternoon, aware that he had come from the hospital, and found him exceptionally glum. She asked about Eva Lind’s condition, thinking it might have worsened, but he said it was stable, and when she asked how he was feeling and whether she could do anything for him, he just shook his head and told her there was nothing to do but wait. She had the impression that the waiting was proving a terrible strain on him, but did not risk broaching the subject. Long experience had taught her that Erlendur had no need to talk about himself to others.

Mikkelina lived on the ground floor in a small block of flats in Breidholt. Her home was small but cosy and while she was in the kitchen making coffee Erlendur walked around the sitting room looking at pictures of what he assumed to be her family. There were not many photographs and none seemed to be from the hill.

She began with a short account of herself while she was going about her business in the kitchen and they listened to her from the sitting room. She started school late, approaching 20 — at the same time as she had her first therapy for her handicap — and she made enormous progress. Erlendur felt she rather skated over her own story, but did not remark on it. In the course of time Mikkelina completed secondary school with extramural classes, enrolled at the university and graduated in psychology. By then she was in her forties. Now she was retired.

She had adopted the boy she called Simon before she went to university. Starting a family would have been difficult for reasons she did not need to go into, she said, with a sardonic smile.

She visited the hill regularly in spring and summer, to look at the redcurrant bushes, and in the autumn she picked berries to make jam. She still had a jar with a little left in it from last autumn’s batch and let them have a taste. Elinborg, a doyenne of cooking, praised her for it. Mikkelina told her to keep the rest and apologised for how little there was.

Then she told them how she had seen the city growing over the years and decades, first stretching out to Breidholt and then Grafarvogur, then at lightning speed along the road to Mosfellsbaer and finally up to Grafarholt, the hill where she had once lived and acquired some of her most painful memories.

“I really only have bad memories of that place,” she said. “Apart from that short summer.”

“Were you born with this disability?” Elinborg asked. She tried to phrase the question as politely as possible, but she decided there was no way of doing so.

“No,” Mikkelina said. “I fell ill when I was three. Went to hospital. Mum told me that parents were forbidden to stay in the wards with their children. She couldn’t understand such a heartless and repulsive rule: not being allowed to stay with a child that was seriously ill or even on the verge of death. It took her several years to realise I could regain what I had lost with therapy, but my stepfather never let her care for me, send me to the doctor or find out about cures. I have a memory from before I was ill, I don’t know whether it’s a dream or real — the sun is shining and I’m in the garden of a house, probably where my mother was a maid, and I’m running at full pelt, squealing, and Mum seems to be chasing me. I don’t remember anything else. Just that I could run around as I pleased.”

Mikkelina smiled.

“I often have that sort of dream. Where I’m healthy and can move as I want, not wagging my head all the time I talk, and I have control over my facial muscles, they don’t pull my features all over the place.”

Erlendur put down his cup.

“You told me yesterday you named your son after your half-brother, Simon.”

“Simon was a wonderful boy. There was none of his father in him. At least I never saw it. He was like Mum. Kind, understanding and helpful. He had endless pity, that child. Hated his father, and his hatred did him harm. He should never have needed to hate anything. And like the rest of us he was smitten with fear throughout his childhood. Terrified when his father went on the rampage. He watched our mother being beaten to a pulp. I used to hide my head under the quilt, but I noticed that Simon sometimes stood watching the attacks, as if he was steeling himself to tackle it, later, when he was strong enough to stand up to his father. When he was big enough to sort him out.

“Sometimes he tried to intervene. Stood in front of our mother, defying him. Mum feared that more than the beatings. She couldn’t bear the thought that anything would happen to her children.

“Such an amazingly kind boy, that Simon.”

“You talk about him as though he’s still a child,” Elinborg said. “Did he die?”

Mikkelina smiled, but said nothing.

“And Tomas?” Erlendur said. “There were only three of you.”

“Yes, Tomas,” Mikkelina said. “He was different from Simon. Their father could tell that.”

Mikkelina fell silent.

“Where did your mother phone?” Erlendur asked. “Before she went back to the hill?”

Without answering him either, Mikkelina stood up and went into her bedroom. Elinborg and Erlendur exchanged glances. A moment later Mikkelina came back holding a piece of paper. She unfolded the note, read it and handed it to Erlendur.

“Mum gave me this note,” she said. “I clearly remember Dave sliding it across the table to her, but we were never allowed to know what it said. Mum didn’t show me it until later. Years later.”

Erlendur read the message.

“Dave got an Icelander or a soldier who spoke Icelandic to write the note for him. Mum always kept it, and, of course, I’ll take it to the grave with me.”

Erlendur looked at the note. Although written in clumsy capitals, the words were very clear.

“Mum and Dave talked about her contacting him as soon as my stepfather got out of prison, and he would come to help her. I don’t know the exact arrangements.”