After Berger and Blomkvist take a walk around Hedeby Island on a rare sunny day, they stop in to visit Vanger on their way home. Vanger starts questioning Berger about Millennium's financial state and, as she reveals the difficulties the publication is facing, Vanger offers to become a silent partner. Vanger suggests that he would be able to help the magazine financially, and that his presence on the board would bother Wennerstrom. Blomkvist is surprised by this turn of events, and after he and Berger leave, he accuses her of having known Vanger's plan in advance. Berger confirms Blomkvist's suspicion after they have dinner with Vanger and go over the details of such a partnership.
After Berger leaves town, Blomkvist mopes around for awhile and then dives back into Harriet's case. He learns, by reading her diary and Morell's police reports, that Harriet had changed during the year right before her disappearance. She had become more aloof and distant with her friends, although not with her cousin, Anita Vanger (Harald's daughter). Harriet also wrote five mysterious names and numbers in the back of her diary, which, despite painstaking effort, Morell was never able to discover the meaning of. Blomkvist realizes that to further the Harriet investigation, he needs to start fresh. Unsure of how to begin, he decides to pay Cecilia Vanger a visit. After Blomkvist assures Cecilia that he's there to see her as a neighbor and not as part of his job, Cecilia seduces him and the two spend the night together.
Switching focus back to Salander, the narrative finds her arriving at Bjurman's office, asking him for money because her laptop broke. Shortly after her arrival, he assaults her sexually. Although Salander is tempted to attack him with a mail opener, she restrains herself, remaining stonily silent and keeping in mind violence might lead to more negative consequences. After his assault on her, Bjurman writes her a check from her bank account and warns her to keep quiet about what has happened.
Chapter 11 develops further the warm and cold motif, explores Blomkvist and Berger's trust in each other, and draws a parallel between Harriet and Salander. The chapter starts off with a description of Berger and Blomkvist's walk. Berger's presence is depicted as being the cause of the warm spell and the sunny day. Here, Berger is an outsider and ally to Blomkvist; she is able to dispel some of the cold surrounding the dysfunctional and mysterious Vanger family. However, Berger's decision to go behind Blomkvist's back to make a deal with Vanger foreshadows problems between Berger and Blomkvist. Will they continue to trust each other? Will their different relationships to Vanger come between them? Additionally, how does Blomkvist's decision to sleep with Cecilia affect Berger and Blomkvist's partnership?
Also of importance in this chapter are the increasingly parallel situations of Salander and Harriet. As more information surfaces about Harriet's life and changing personality in the year before she vanished, signs point more clearly to something troubling having happened to her. For instance, she seeks solace in religion yet refuses to open up with her closest friends. Similarly, Salander's troubled teenage years have influenced her personality, also making her secretive and reserved with others. This parallel between the two women will grow more refined and complex as the novel progresses.