'I've just spoken to Jörne,' said Wallander. 'The poison that killed Alexandersson could very well have been administered without him noticing it. It's not possible to say precisely how fast it works. Jörne guessed it would be at least half an hour. When death does come, it happens very quickly.'

'So we're right in our suppositions so far,' said Hansson. 'Does this poison have a name?'

Wallander read out the complicated chemical description he had written down on his notepad.

Then he told them about the conversation he'd had with Martin Stenholm in Svarte.

'I don't know why,' he said, 'but I can't help feeling we'll find the solution to our problem in that doctor's house.'

'A doctor knows about poisons,' Rydberg said. 'That's always a start.'

'You're right, of course,' said Wallander. 'But there's something else too. I can't put my finger on it, though.'

'Why don't I run a search through the registers?' asked Hansson. 'It's too bad Martinsson is sick. He's the best at that sort of thing.'

Wallander nodded. Then an idea struck him.

'Do one for his wife as well. Kajsa Stenholm.'

The investigation was put on hold for the Valpurgis Night holiday and the weekend. Wallander spent a large part of his free time at his father's house. He spent one afternoon repainting the kitchen. He also called Rydberg, for no other reason than the fact that Rydberg was as solitary as he was. But when Wallander called, Rydberg turned out to be drunk, and the conversation was a very short one.

On Monday, 4 May, he was back at the police station early. While he waited to hear if Hansson had found anything of interest in the registers, he resumed his work on the gang smuggling stolen cars into Poland. It wasn't until eleven the next morning that Hansson eventually showed up.

'I can't find a thing about Martin Stenholm,' he said. 'It looks as if he's never done a dishonest thing in his whole life.'

Wallander wasn't in the least surprised. He had been aware from the start that they could be heading into a cul-de-sac.

'What about his wife?'

Hansson shook his head.

'Even less,' said Hansson. 'She was a prosecutor in Nynäshamn for many years.'

Hansson put a file full of papers on Wallander's desk.

'I'll go and talk to the taxi drivers again,' he said. 'Perhaps they saw something without realising it.'

When Hansson had left, Wallander opened the file. It took him an hour to work his way carefully through all the documents. For once Hansson hadn't overlooked anything. Even so, Wallander was convinced that Alexandersson's death had something to do with the old doctor. He knew without knowing, as so many times before. He didn't trust his intuition, it was true, but he couldn't deny that it had served him well many times in the past. He called Rydberg, who came to his office immediately. Wallander handed him the file.

'I'd like you to read through this,' he said. 'Neither Hansson nor I can see anything of interest, but I'm sure we're missing something.'

'We can forget Hansson,' Rydberg said, making no attempt to disguise the fact that his respect for his colleague was limited.

Late that afternoon Rydberg returned the file, shaking his head. He hadn't found anything either.

'We'll have to start again from the beginning,' said Wallander. 'Let's meet here in my office tomorrow morning and decide where we go from here.'

An hour later Wallander left the police station and drove to Svarte. Once again he took a long walk along the beach. He didn't see another soul. Then he sat in his car and read one more time through the material Hansson had given him. What is it that I'm missing? he asked himself. There is a link between this doctor and Göran Alexandersson. It's just me who can't see what it is.

He drove back to Ystad and took the file home with him to Mariagatan. They had lived in the same three-room apartment ever since they moved to Ystad twelve years earlier.

He tried to relax, but the file gave him no peace. As midnight approached, he sat down at the kitchen table and went through it one more time. Although he was very tired, he did in fact find one detail that caught his attention. He knew it might well have no significance. Nevertheless, he decided to look into it early the following morning.

He slept badly that night.

He was back at the police station by 7 a.m. Ystad was enveloped in drizzle. Wallander knew the man he was looking for was just as much of an early bird as he was. He went to the part of the building that housed the prosecutors and knocked on Per Åkeson's door. As usual, the room was in chaos. Åkeson and Wallander had worked together for many years and had great faith in each other's judgement. Åkeson pushed his glasses up on top of his head and looked at Wallander.

'Are you here already?' he said. 'So early? That must mean you have something important to tell me.'

'I don't know if it's important,' Wallander said, 'but I need your help.'

Wallander moved several bundles of paper from the visitor's chair to the floor and sat down. Then he summarised briefly the circumstances of Göran Alexandersson's death.

'It sounds very strange,' said Åkeson when Wallander had finished.

'Strange things do happen now and then,' Wallander said. 'You know that as well as I do.'

'I don't think you've come here at seven in the morning just to tell me this. I hope you're not going to suggest we should arrest that doctor?'

'I need your help with his wife,' Wallander said. 'Kajsa Stenholm. A former colleague of yours. She worked in Nynäshamn for many years. But she had several temporary assignments too. Seven years ago she was filling in for somebody in Stockholm. It happened to be at the same time as Alexandersson's son's murder. I need your help to find out if there is a connection between those two events.'

Wallander leafed through his papers before continuing.

'The son was called Bengt,' he said eventually. 'Bengt Alexandersson. He was eighteen when he was killed.'

Åkeson leaned his chair back and looked at Wallander with a furrowed brow.

'What do you think might have happened?' he asked.

'I don't know,' said Wallander, 'but I want to find out if there could be some sort of link. If Kajsa Stenholm was somehow involved in the investigation into the death of Bengt Alexandersson.'

'I take it you want to know as soon as possible?'

Wallander nodded.

'You should know by now that my patience is more or less nonexistent,' he said, rising to his feet.

'I'll see what I can do,' said Åkeson. 'But don't expect heaven and earth to be moved.'

When Wallander passed through reception on his way back to his office, he asked Ebba to send Rydberg and Hansson in to see him as soon as they came in.

'How are you nowadays?' Ebba asked. 'Are you getting a good night's sleep?'

'I sometimes feel I'm sleeping too much,' said Wallander evasively. Ebba was reception's stalwart and kept a maternal watch on everybody's state of health. Wallander sometimes had to fend off her concern in as friendly a way as possible.

Hansson came to Wallander's office at about a quarter past eight, and Rydberg followed soon afterwards. Wallander summarised briefly what he had found in what were already being called 'Hansson's papers'.

'We'll have to wait and see what Åkeson comes up with,' said Wallander. 'Maybe it's just a meaningless guess on my part. But on the other hand, if it does turn out that Kajsa Stenholm was assigned to Stockholm when Bengt Alexandersson was murdered and that she was involved in the investigation, we've found the link we've been looking for.'

'Didn't you say she was on her deathbed?' wondered Rydberg.

'That's what her husband claimed,' Wallander said. 'I haven't actually met her.'