Wallander got up and went into Svedberg's study. First he looked around for a minute, then he sat down at the desk. He let images from the investigation come to him. There were the three postcards that Eva Hillström had doubted from the very beginning. Wallander hadn't believed her; no one had. It had been inconceivable that someone would send fake postcards. But now they had found her daughter dead, they knew that the postcards had been sent by someone else. Someone had travelled all over Europe, to Hamburg, Paris and Vienna for this. Why? Even if the three young people were not killed on Midsummer's Eve, there was no doubt that they were killed before the last postcard came from Vienna. But what was the reason for this false trail?

Wallander stared blankly out into the dimly lit room.

I'm afraid, he thought. I've never believed in pure evil. There are no evil people, no one with brutality in their genes. There are evil circumstances and environments, not evil per se. But here I sense the actions of a truly darkened mind.

Wallander reached for Svedberg's pocket calendar and went through it again. There was the recurring name, "Adamsson". Could this be the surname of the woman in the photograph whom Sture Björklund told them was called Louise? Louise Adamsson. He went back to the kitchen and looked in the phone book. There was no Louise Adamsson listed. She could be married, of course, and have a different surname. He made a mental note to ask Martinsson to find out what Svedberg had done on the days marked "Adamsson" in his calendar.

He turned out the light and went to the living room. Here someone had walked across the floor with a shotgun in his hand. It had been aimed and fired at Svedberg's head, then thrown to the floor and left behind. Wallander tried to think whether this marked the beginning or end of a series of events. Or was it part of something even larger? He almost didn't have the energy to follow this last thought to its conclusion. Was there really someone out there who was going to continue the senseless killing? He didn't know. Nothing gave him the mental foothold he was looking for. He walked over to the place where the shotgun had been found and tried to see where Svedberg must have been sitting. The cement mixer would have been rumbling on the street. Two shots, Svedberg thrown to the ground – probably dead before he even hit the floor. Wallander didn't hear any argument or raised voices, only the dry shots from the gun. He changed his position and walked over to the chair that lay on the ground.

You let in a person you know, someone you are not afraid of. Or else someone enters who has his own key. Perhaps someone picks the lock. There are no marks on the door; he didn't use a crowbar. We'll assume it's a he. He has a shotgun, or else you keep an unregistered shotgun in the flat. A shotgun that is loaded, and that the person you have let in knows about. There are so many questions, but in the end it comes down to a who and a why. Only one who. And one lone why.

He went back to the kitchen and called the hospital. Luckily, the doctor he had spoken to before was in.

"Isa Edengren is doing well. She'll be released tomorrow or the day after."

"Has she said anything?"

"Not really. But I think she's happy you found her."

"Does she know it was me?"

"Shouldn't we have told her that?"

"What was her reaction?"

"I don't think I understand your question."

"How did she react when she was told that a policeman had come looking for her?"

"I don't know."

"I need to talk to her as soon as possible."

"Tomorrow will be fine."

"I'd rather talk to her tonight. I need to talk to you, too."

"It sounds rather urgent."

"It is."

"I'm actually on my way out. It would be more convenient to talk tomorrow."

"I wish it were that unimportant," Wallander said. "But I have to ask you to stay. I'll be there in ten minutes."

"Has something happened?"

"Yes. Something I don't think you could possibly imagine."

Wallander drank a glass of water and left the flat. It was still warm outside, with only a faint breeze.

When he arrived at the ward where Isa Edengren was being kept, the doctor was waiting for him. They went into an empty office and Wallander closed the door. On the way over he had decided to level with the doctor completely. He told him what they had found out in the nature reserve, that three young people had been murdered, and that Isa Edengren was meant to have been with them. The only detail he left out was the fact that they had been dressed up. The doctor listened in disbelief.

"I thought about going into pathology," he said afterwards. "But hearing this I'm glad I decided against it."

"You're right. It was a terrible sight."

The doctor got up. "I take it you want to see her now."

"Just one more thing. Naturally I'd like you not to mention this to anyone."

"Doctors have to take an oath."

"So do police officers. But information seems to have a way of getting out anyway."

They stopped outside Isa's door.

"I'll just make sure she's awake."

Wallander waited. He didn't like hospitals. He wanted to leave as soon as possible. He remembered what Dr Göransson said about checking his blood-sugar levels. It was apparently a very simple test. The doctor came back out.

"She's awake."

"One more thing," Wallander said. "This will sound strange, but can you check my blood-sugar level?"

The doctor looked at him with astonishment.

"Why?"

"I have an appointment with one of your colleagues tomorrow morning that I won't be able to attend. But I was going to have it checked."

"Are you diabetic?"

"No. My blood-sugar level is too high."

"Then you're diabetic."

"I just want to know if you can measure it or not. I don't have my insurance card with me but maybe you could make an exception in my case."

A nurse walked by and the doctor stopped her.

"Could you check this man's blood-sugar level? He's going to speak with Edengren afterwards."

"Of course."

The nurse's name tag said "Brundin". Wallander thanked the doctor for his help and followed the nurse. She pricked his finger and squeezed a drop of blood onto a strip of tape in a machine that looked like a Walkman.

"It's very high – 15.5," she said.

"It's way too high," Wallander said. "That's all I wanted to know."

She looked closely at him, but in a friendly way.

"You're a little on the heavy side," she said.

Wallander nodded. He felt suddenly ashamed of himself, like a naughty child.

He went back to Isa Edengren's room. He had expected her to be lying in bed, but she was curled up in an armchair with a blanket drawn tightly around her. The only light in the room came from the bedside lamp. As he came closer he saw something like fear in her eyes. He put out his hand and introduced himself, then sat down on a stool next to her.

She doesn't know what's happened, he thought. That three of her closest friends are dead. Or does she suspect it already? Has she been waiting for this discovery? Is that why she couldn't take it any longer?

He pulled his stool around so he was facing her. Her eyes never left him. When he had first walked into the room she had reminded him of Linda. Linda had also tried to commit suicide, at the age of 15. Wallander later realised it was part of the series of events that had led Mona to leave him. He had never really understood it, even though he and Linda talked about it years later. There was something there that he would never quite grasp. He wondered if he would be able to understand why this girl had tried to take her life.

"I'm the one who found you," he said. "I know you know that already. But you don't know why I came out to Skårby. You don't know why I walked around the back of the locked house and kept looking for you until I found you in the gazebo where you were sleeping."