Martin and Blomkvist continue talking while Martin waits for Salander to return to the cabin so he can capture her as well. During this discussion, Blomkvist realizes that Martin has continued killing women since he was a teenager. Martin's initiation into the practice was at the hands of his father, Gottfried, who raped and murdered women, and who also sexually assaulted his son.
Back at the archives, Salander makes a parallel discovery, realizing that in addition to Gottfried, Martin is also a killer. She leaves the archives and, finding Blomkvist not at home, reviews the surveillance tape. Salander sees Blomkvist leaving, and Martin attempting to enter the cabin with his old key. A feeling of urgent doom settles over her.
Martin, having left Blomkvist to try to enter the cabin, comes back and fetches the new key from him. This time, they talk about Harriet. Blomkvist realizes that Martin has no idea what happened to her, but that both Martin and Gottfried tried to make her part of their sick world. Martin, furious that Blomkvist won't tell him what he's learned about Harriet, holds him up against the wall, putting a leather noose around his neck. At this moment, Salander bursts in, swinging a golf club with which she brutally beats Martin. She's able to incapacitate Martin and then release Blomkvist from the noose. While Salander helps Blomkvist, Martin stumbles up the stairs to his garage where he hops into his car and speeds off. Salander follows on her motorbike and watches as Martin slams into a semi-truck, killing himself in a fiery explosion. Salander narrowly avoids the crash and returns to Martin's house to help Blomkvist home, being careful to wipe their fingerprints from the house. Salander cares for the wounded Blomkvist when they return home, and the wounded man promptly falls asleep.
In Chapter 24, the symbol of fire returns, and Salander's toughness in the face of danger is shown once again. Martin's death in a fiery car crash has several symbolic overtones. First, the violent event unites his death with the other deaths he and his father have caused over the years, as several of the victims were also burnt. Secondly, due to his sociopathic nature, Martin is unable to see a solution that doesn't involve violence. Killing himself becomes the only way he can escape punishment.
Secondly, Salander's quick thinking and steely resolve come to her rescue again. Her quick attack on Martin recalls her attack on Bjurman. Both aggressive acts are quite violent, but unlike her assailants, these attacks are justified because they're provoked and occur when it's a matter of life or death. Furthermore, because Salander is able to resolve her problems via her smarts or violence if necessary, she continues to see no need to involve the police. As before, her troubled relationship with authority comes to influence her current decision-making. Salander sees herself as the only authority she has to answer to.