The Girl with the Dragon Tattoo by Stig Larsson

Forty years ago, Harriet Vanger disappeared off the secluded island owned and inhabited by the powerful Vanger family. There was no corpse, no witnesses, no evidence. But her uncle, Henrik, is convinced that she was murdered by someone in her own family - the deeply dysfunctional Vanger clan. Disgraced journalist Mikael Blomqvist is hired to investigate, but when he links Harriet's disappearance to a string of gruesome murders from forty years ago, he needs a competent assistant - and he gets one: computer hacker Lisbeth Salander - a tattoed, truculent, angry girl who rides a motorbike like a Hell's Angel and handles makeshift weapons with the skill born of remorseless rage. This unlikely pair form a fragile bond as they delve into the sinister past of this island-bound, tightly-knit family. But the Vangers are a secretive lot, and Mikael and Lisbeth are about to find out just how far they're prepared to go to protect themselves - and each other.