The Girl Who Played with Fire by Stieg Larsson

Second Hand 

Part blistering espionage thriller, part riveting police procedural, and part piercing expose on social injustice, "The Girl Who Played with Fire" is a masterful, endlessly satisfying novel.
Mikael Blomkvist, crusading publisher of the magazine "Millennium," has decided to run a story that will expose an extensive sex trafficking operation. On the eve of its publication, the two reporters responsible for the article are murdered, and the fingerprints found on the murder weapon belong to his friend, the troubled genius hacker Lisbeth Salander. Blomkvist, convinced of Salander's innocence, plunges into an investigation. Meanwhile, Salander herself is drawn into a murderous game of cat and mouse, which forces her to face her dark past."