In Stockholm, the journalist and chief-editor of the magazine Millennium Mikael Blomkvist is sentenced to three months in prison for slandering the corrupt entrepreneur Hans-Erik Wennerström. Meanwhile the wealth industrialist Henrik Vanger and his lawyer Dirch Frode hire the Milton Security to investigate the life of Mikael, and the hacker Lisbeth Salander finds that he is an honest man. Mikael is invited to travel to Hedeby Island near Hedestadt to meet Henrik at his home that proposes him to investigate who murdered his beloved nephew Harriet that disappeared forty years ago. Mikael moves to Hedeby Island and Henrik delivers all the files of the case. The journalist learns that all the members of the dysfunctional Vanger family are suspect and the three brothers of Henrik were Nazi. Meanwhile Lisbeth is hacking Mikael's computer and she decides to help him with further information about the case. Henrik hires Lisbeth to help Mikael and they discover a series of hideous murders connected to the disappearance of Harriet.