The Girl Who Played with Fire

Lisbeth Salander (Noomi Rapace) purchases an apartment in Stockholm. On returning to Sweden after nearly a year living abroad, Salander reconnects with her former lover Miriam Wu (Yasmine Garbi) and offers her free use of her previous home in return for forwarding her mail. Later, Salander confronts Nils Bjurman (Peter Andersson) after hacking into his mail and discovering he has an appointment booked with a tattoo removal specialist. Threatening him with his own gun, she warns him not to remove the tattoo that she etched on his abdomen as revenge for sexually abusing her, marking him as "a pervert, a rapist and a sadistic pig."
Millennium magazine welcomes Dag Svensson (Hans Christian Thulin), a new journalist who is writing an exposÃ© on prostitution and human trafficking in Sweden. Dag's girlfriend, Mia Bergman, is writing her doctoral thesis on sex trafficking. Dag is nearly finished with the story and is confronting those who will be exposed by the article. Dag and his girlfriend are about to leave on a holiday and ask Mikael Blomkvist (Michael Nyqvist) to come to his apartment and collect some photographs. At the same time Dag also asks Mikael to inquire about someone called "Zala," who may have a connection to his present research. Mikael arrives at their apartment late at night to collect photographs for the article but finds the two sources lying dead. The murder weapon is tracked to Bjurman who is also deceased. Lisbeth Salander is the prime suspect, as her fingerprints happen to be on the gun as well. Salander tells Blomkvist that she did not kill anyone and that he needs to find the mysterious "Zala."
In an effort to find Lisbeth's residence, Mikael contacts her boxing trainer and friend, Paolo Roberto. While he is unaware of Salander's whereabouts, Paolo does know Miriam, who also trained with them, and promises to pay her a visit. Near her apartment, Paolo witnesses Miriam being kidnapped by strongman Niedermann. Paolo follows his car to a deserted barn, where he hears him beat Miriam for information about Salander. Paolo comes in to rescue her but Niedermann is more than a match for the skilled boxer. Niedermann sets the barn aflame to finish the job, but the two manage to escape.
News breaks of the attack and Paolo gives his account to the police. After Blomkvist leaves information he has discovered about the case on his computer for Salander to hack into and read, she leaves a message to him saying, "Thank you for being my friend." He realizes that she intends to set out alone to find the man who framed her and that she may not survive. A disguised Salander visits Miriam in hospital to apologize for getting her involved. Without giving anything away, Salander confirms the police sketch of Niedermann with Miriam and then disappears. Knowing now that he is Salander's friend, Miriam calls Blomkvist to the hospital to give him keys that Lisbeth accidentally dropped during her visit. Noticing that one of them is for a post office box, Mikael is able to access and read Salander's mail and locate her apartment. Meanwhile, Salander continues her efforts to find Niedermann by patiently staking out his post office box. She eventually sees someone retrieve his mail and follows him to a small house near Gosseberga. Researching through the material in Lisbeth's apartment Blomkvist finds the video of Bjurman raping Salander.
In the offices of Millennium magazine, Paolo explains he tracked down Niedermann and learned that he has congenital analgesia which makes him doubly formidable because he cannot feel pain. They trace Niedermann to a company owned by "Karl Axel Bodin." Blomkvist has Erika Berger make copies of the documents including the 1993 police report, forwards the originals to Bublanski and sets out to find Salander.
Salander crosses the grounds and enters the Gosseberga house, but Niedermann has been alerted by motion detectors and knocks her out. She awakens to see her father, Alexander Zalachenko, an old man who walks with a stick and is heavily scarred by the burns she inflicted as a child. He dismisses her mother (who is now dead) as a whore and belittles her rape at the hands of Bjurman. He reveals that Niedermann is her half-brother. Niedermann killed Bjurman to prevent him from revealing any of Zalachenko's secrets. Zalachenko is confident he will not be caught, since being an invalid means the idea of his involvement in the murders lacks plausibility.
They lead Lisbeth to a shallow grave in the woods. She tells him the police will find him soon and all that he has said has been published online through her hidden cellphone. Seeing through her bluff, he shoots Lisbeth at close range several times as she attempts to escape and buries her alive. Left for dead, Salander digs her way out using her silver-plated cigarette case gifted to her by Wu. Hidden in the woodshed, she surprises Zalachenko with an axe. She then keeps Niedermann at bay, both with Zalachenko's gun and Niedermann's delusions, just as Blomkvist comes coasting up the driveway. Ambulances and police arrive to take away Salander and Zalachenko who are both very badly injured.

Question: How does Niedermann finish the job?
Answer: sets barn on fire