Blomkvist asked her how much she had heard of what Martin said.

"Not much. I got there when he was asking you about what happened to Harriet, just before he hung you up by the noose. I left for a few minutes to go back and find a weapon."

"Martin had no idea what happened to Harriet," Blomkvist said.

"Do you believe that?"

"Yes," Blomkvist said without hesitation. "Martin was dafter than a syphilitic polecat - where do I get these metaphors from? - but he confessed to all the crimes he had committed. I think that he wanted to impress me. But when it came to Harriet, he was as desperate as Henrik Vanger to find out what happened."

"So... where does that take us?"

"We know that Gottfried was responsible for the first series of murders, between 1949 and 1965."

"OK. And he brought on little Martin."

"Talk about a dysfunctional family," Blomkvist said. "Martin really didn't have a chance."

Salander gave him a strange look.

"What Martin told me - even though it was rambling - was that his father started his apprenticeship after he reached puberty. He was there at the murder of Lea in Uddevalla in 1962. He was fourteen, for God's sake. He was there at the murder of Sara in 1964 and that time he took an active part. He was sixteen."

"And?"

"He said that he had never touched another man - except his father. That made me think that... well, the only possible conclusion is that his father raped him. Martin called it 'his duty.' The sexual assaults must have gone on for a long time. He was raised by his father, so to speak."

"Bullshit," Salander said, her voice as hard as flint.

Blomkvist stared at her in astonishment. She had a stubborn look in her eyes. There was not an ounce of sympathy in it.

"Martin had exactly the same opportunity as anyone else to strike back. He killed and he raped because he liked doing it."

"I'm not saying otherwise. But Martin was a repressed boy and under the influence of his father, just as Gottfried was cowed by his father, the Nazi."

"So you're assuming that Martin had no will of his own and that people become whatever they've been brought up to be."

Blomkvist smiled cautiously. "Is this a sensitive issue?"

Salander's eyes blazed with fury. Blomkvist quickly went on.

"I'm only saying that I think that a person's upbringing does play a role. Gottfried's father beat him mercilessly for years. That leaves its mark."

"Bullshit," Salander said again. "Gottfried isn't the only kid who was ever mistreated. That doesn't give him the right to murder women. He made that choice himself. And the same is true of Martin."

Blomkvist held up his hand.

"Can we not argue?"

"I'm not arguing. I just think that it's pathetic that creeps always have to have someone else to blame."

"They have a personal responsibility. We'll work it all out later. What matters is that Martin was seventeen when Gottfried died, and he didn't have anyone to guide him. He tried to continue in his father's footsteps. In February 1966, in Uppsala."

Blomkvist reached for one of Salander's cigarettes.

"I won't speculate about what impulses Gottfried was trying to satisfy or how he himself interpreted what he was doing. There's some sort of Biblical gibberish that a psychiatrist might be able to figure out, something to do with punishment and purification in a figurative sense. It doesn't matter what it was. He was a cut and dried serial killer.

"Gottfried wanted to kill women and clothe his actions in some sort of pseudo-religious clap-trap. Martin didn't even pretend to have an excuse. He was organised and did his killing systematically. He also had money to put into his hobby. And he was shrewder than his father. Every time Gottfried left a body behind, it led to a police investigation and the risk that someone might track him down, or at least link together the various murders."

"Martin Vanger built his house in the seventies," Salander said pensively.

"I think Henrik mentioned it was in 1978. Presumably he ordered a safe room put in for important files or some such purpose. He got a soundproofed, windowless room with a steel door."

"He's had that room for twenty-five years."

They fell silent for a while as Blomkvist thought about what atrocities must have taken place there for a quarter of a century. Salander did not need to think about the matter; she had seen the videotapes. She noticed that Blomkvist was unconsciously touching his neck.

"Gottfried hated women and taught his son to hate women at the same time as he was raping him. But there's also some sort of undertone... I think Gottfried fantasised that his children would share his, to put it mildly, perverted world view. When I asked about Harriet, his own sister, Martin said: 'We tried to talk to her. But she was just an ordinary cunt. She was planning to tell Henrik.'"

"I heard him. That was about when I got down to the basement. And that means that we know what her aborted conversation with Henrik was to have been about."

Blomkvist frowned. "Not really. Think of the chronology. We don't know when Gottfried first raped his son, but he took Martin with him when he murdered Lea Persson in Uddevalla in 1962. He drowned in 1965. Before that, he and Martin tried to talk to Harriet. Where does that lead us?"

"Martin wasn't the only one that Gottfried assaulted. He also assaulted Harriet."

"Gottfried was the teacher. Martin was the pupil. Harriet was what? Their plaything?"

"Gottfried taught Martin to screw his sister." Salander pointed at the Polaroid prints. "It's hard to determine her attitude from these two pictures because we can't see her face, but she's trying to hide from the camera."

"Let's say that it started when she was fourteen, in 1964. She defended herself - couldn't accept it, as Martin put it. That was what she was threatening to tell Henrik about. Martin undoubtedly had nothing to say in this connection; he just did what his father told him. But he and Gottfried had formed some sort of... pact, and they tried to initiate Harriet into it too."

Salander said: "In your notes you wrote that Henrik had let Harriet move into his house in the winter of 1964."

"Henrik could see there was something wrong in her family. He thought it was the bickering and friction between Gottfried and Isabella that was the cause, and he took her in so that she could have some peace and quiet and concentrate on her studies."

"An unforeseen obstacle for Gottfried and Martin. They couldn't get their hands on her as easily or control her life. But eventually... Where did the assault take place?"

"It must have been at Gottfried's cabin. I'm almost positive that these pictures were taken there - it should be possible to check. The cabin is in a perfect location, isolated and far from the village. Then Gottfried got drunk one last time and died in a most banal way."

"So Harriet's father had attempted to have sex with her, but my guess is that he didn't initiate her into the killing."

Blomkvist realised that this was a weak point. Harriet had made note of the names of Gottfried's victims, pairing them up with Bible quotes, but her interest in the Bible did not emerge until the last year, and by then Gottfried was already dead. He paused, trying to come up with a logical explanation.

"Sometime along the way Harriet discovered that Gottfried had not only committed incest, but he was also a serial sex murderer," he said.

"We don't know when she found out about the murders. It could have been right before Gottfried drowned. It might also have been after he drowned, if he had a diary or had saved press cuttings about them. Something put her on his track."

"But that wasn't what she was threatening to tell Henrik," Blomkvist said.

"It was Martin," Salander said. "Her father was dead, but Martin was going on abusing her."

"Exactly."

"But it was a year before she took any action."

"What would you do if you found out that your father was a murderer who had been raping your brother?"

"I'd kill the fucker," Salander said in such a sober tone that Blomkvist believed her. He remembered her face as she was attacking Martin Vanger. He smiled joylessly.

"OK, but Harriet wasn't like you. Gottfried died before she managed to do anything. That also makes sense. When Gottfried died, Isabella sent Martin to Uppsala. He might have come home for Christmas or other holidays, but during that following year he didn't see Harriet very often. She was able to get some distance from him."

"And she started studying the Bible."

"And in light of what we now know, it didn't have to be for any religious reasons. Maybe she simply wanted to know what her father had been up to. She brooded over it until the Children's Day celebration in 1966. Then suddenly she sees her brother on Jarnvagsgatan and realises that he's back. We don't know if they talked to each other or if he said anything. But no matter what happened, Harriet had an urge to go straight home and talk to Henrik."

"And then she disappeared."

After they had gone over the chain of events, it was not hard to understand what the rest of the puzzle must have looked like. Blomkvist and Salander packed their bags. Before they left, Blomkvist called Frode and told him that he and Salander had to go away for a while, but that he absolutely wanted to see Henrik Vanger before they left.

Blomkvist needed to know what Frode had told Henrik. The man sounded so stressed on the telephone that Blomkvist felt concerned for him. Frode said that he had only told him that Martin had died in a car accident.

It was thundering again when Blomkvist parked outside Hedestad Hospital, and the sky was filled once more with heavy rain clouds. He hurried across the car park just as it started to rain.

Vanger was wearing a bathrobe, sitting at a table by the window of his room. His illness had left its mark, but Vanger had regained some colour in his face and looked as if he were on the path to recovery. They shook hands. Blomkvist asked the nurse to leave them alone for a few minutes.

"You've been avoiding me," Vanger said.

Mikael nodded. "On purpose. Your family didn't want me to come at all, but today everyone is over at Isabella's house."

"Poor Martin," Vanger said.

"Henrik. You gave me an assignment to dig up the truth about what happened to Harriet. Did you expect the truth to be painless?"

The old man looked at him. Then his eyes widened.

"Martin?"

"He's part of the story."

Henrik closed his eyes.

"Now I have got a question for you," Blomkvist said.

"Tell me."

"Do you still want to know what happened? Even if it turns out to be painful and even if the truth is worse than you imagined?"

Henrik gave Blomkvist a long look. Then he said, "I want to know. That was the point of your assignment."

"OK. I think I know what happened to Harriet. But there's one last piece of the puzzle missing before I'm sure."

"Tell me."

"No. Not today. What I want you to do right now is to rest. The doctors say that the crisis is over and that you're getting better."

"Don't you treat me like a child, young man."

"I haven't worked it all out yet. What I have is a theory. I am going out to find the last piece of the puzzle. The next time you see me, I'll tell you the whole story. It may take a while, but I want you to know that I'm coming back and that you'll know the truth."

Salander pulled a tarpaulin over her motorcycle and left it on the shady side of the cabin. Then she got into Blomkvist's borrowed car. The thunderstorm had returned with renewed force, and just south of Gavle there was such a fierce downpour that Blomkvist could hardly see the road. Just to be safe, he pulled into a petrol station. They waited for the rain to let up, so they did not arrive in Stockholm until 7:00 that evening. Blomkvist gave Salander the security code to his building and dropped her off at the central tunnelbana. His apartment seemed unfamiliar.

He vacuumed and dusted while Salander went to see Plague in Sundbyberg. She arrived at Blomkvist's apartment at around midnight and spent ten minutes examining every nook and cranny of it. Then she stood at the window for a long time, looking at the view facing the Slussen locks.

They got undressed and slept.

At noon the next day they landed at London's Gatwick Airport. They were met with rain. Blomkvist had booked a room at the Hotel James near Hyde Park, an excellent hotel compared to all the one-star places in Bayswater where he had always ended up on his previous trips to London.

At 5:00 p.m. they were standing at the bar when a youngish man came towards them. He was almost bald, with a blond beard, and he was wearing jeans and a jacket that was too big for him.

"Wasp?"

"Trinity?" she said. They nodded to each other. He did not ask for Blomkvist's name.

Trinity's partner was introduced as Bob the Dog. He was in an old VW van around the corner. They climbed in through the sliding doors and sat down on folding chairs fastened to the sides. While Bob navigated through the London traffic, Wasp and Trinity talked.

"Plague said this had to do with some crash-bang job."

"Telephone tapping and checking emails in a computer. It might go fast, or it could take a couple of days, depending on how much pressure he applies." Lisbeth gestured towards Blomkvist with her thumb. "Can you do it?"

"Do dogs have fleas?" Trinity said.

Anita Vanger lived in a terrace house in the attractive suburb of St. Albans, about an hour's drive north. From the van they saw her arrive home and unlock the door some time after 7:30 that evening. They waited until she had settled, had her supper, and was sitting in front of the TV before Blomkvist rang the doorbell.