From amazon.com:

The electrifying follow-up to the phenomenal best seller The Girl with the Dragon Tattoo ("An intelligent, ingeniously plotted, utterly engrossing thriller" The Washington Post), and this time it is Lisbeth Salander, the troubled, wise-beyond-her-years genius hacker, who is the focus and fierce heart of the story.

Mikael Blomkvist, crusading journalist and publisher of the magazine Millennium, has decided to publish a story exposing an extensive sex trafficking operation between Eastern Europe and Sweden, implicating well-known and highly placed members of Swedish society, business, and government.

On the eve of publication, the two reporters responsible for the story are brutally murdered. But perhaps more shocking for Blomkvist: the fingerprints found on the murder weapon belong to Lisbeth Salander.

Now, as Blomkvist, alone in his belief in her innocence, plunges into his own investigation of the slayings, Salander is drawn into a murderous hunt in which she is the prey, and which compels her to revisit her dark past in an effort to settle with it once and for all.