Note: this is an English-language adaptation of the Swedish novel trilogy by Stieg Larsson. But with the same setting in Stockholm, Sweden.

On his birthday, Henrik Vanger (Christopher Plummer), retired CEO of Vanger Industries, receives a pressed flower in the mail from an anonymous sender and phones retired inspector Gustaf Morell (Donald Sumpter).

Co-owner of the magazine Millennium, Mikael Blomkvist (Daniel Craig) is swarmed by reporters as he leaves a courthouse, having lost a libel suit leveled against him by corrupt businessman Hans-Erik Wennerstrom (Ulf Friberg). His reputation destroyed and his life savings gone, Blomkvist returns to the office and informs his co-owner Erika Berger (Robin Wright), who is also his lover, that he is resigning.

Dirch Frode (Steven Berkoff), the attorney of Henrik Vanger, meets with Dragan Armansky (Goran Vijnic) at the headquarters of Milton Security, having requested a background check on Blomkvist. Armansky has arranged for Lisbeth Salander (Rooney Mara), a girl in her twenties with multiple tattoos and facial piercings who is his best researcher and computer hacker, to come in and personally report her findings on Blomkvist.

On Christmas, Blomkvist receives a phone call from Frode summoning him to the Vanger estate on Hedeby Island in Hedestad for a face-to-face meeting with Henrik. Upon his arrival, Henrik explains that he is interested in hiring Blomkvist to investigate the murder of his niece Harriet Vanger, who disappeared from the island over 40 years ago. Before she vanished, Harriet would give Henrik a pressed flower for his birthday every year, a tradition that he believes has been continued by the person responsible for her disappearance. Convinced that someone in the family murdered Harriet, Henrik will allow Blomkvist to conduct his investigation out of a cottage on the island, under the guise of writing a memoir about Henrik and his life. Blomkvist is reluctant to accept, until Henrik offers him incriminating evidence that would validate his claims against Wennerstrom.

Lisbeth pays a visit to the home of her legal guardian Holger Palmgren (Bengt C.W. Carlsson) and discovers that he has had a stroke. Ruled legally incompetent as a child, Lisbeth is a ward of the state and she is placed under the guardianship of lawyer Nils Bjurman (Yorick Van Wageningen), who takes full control of her finances and forces her to perform sex acts on him in exchange for access to her money. One night, when she requests money for food, he has Lisbeth come to his apartment, where he handcuffs her to his bed and proceeds to rape and sodomize her, unaware that she has secretly recorded the crime using a hidden camera on her backpack.