Journalist Mikael Blomkvist is found guilty of falsely accusing Wennerström of illegal gun trafficking and fraud. He is sentenced to some time in prison but doesn't have to serve the time right away. Many of his fans believe he is innocent.
He is hired by Henrik Vanger to investigate the 40-year-old murder of his niece, Harriet. Henrik thinks someone in the family did it. Mikael finds some things but doesn't get to far until he enlists the help of a young punk hacker named Lisbeth.
They find out that Harriet knew of a trail of murders of women and that the murderer found out so he also killed her. Turns out that it isn't so. Her father Gottfried and brother Martin committed the murders of all those women. She killed her father after he raped her one day and Martin saw. Henrik had sent him away to boarding school, so she stayed until he came back and she fled in fear, not telling anyone except her cousin Anita. Mikael reunites them.
Lisbeth and Mikael developed a sort of relationship and she visits him while he does his time. She brings him a bunch of info she dug up on Wennerström, which proves he was into illegal drug and arms trafficking. Mikael publishes another article, this time with evidence and Wennerström commits suicide.
Lisbeth disguises herself and withdraws millions from one of Wennerström accounts in the Cayman Islands