Financial journalist Mikael Blomkvist has made his living uncovering the corrupt and crooked practices of Stockholm's leading financiers in his magazine, Millennium. But one expose unexpectedly backfires, and Blomkvist's reputation is in tatters. When he is offered an investigative job by powerful businessman Henrik Vanger, he is in no position to refuse. But he is surprised to find it has nothing to do with high finance - this time, it is a case of murder.

Many years ago, Henrik's niece, Harriet, disappeared during a family gathering on the island owned and inhabited by the Vangers. No-one saw her leave the island, and no body was ever found. Even so, Henrik is convinced that she was murdered by a member of his own family - the tightly knit but dysfunctional Vanger clan.

Blomkvist is soon in over his head. He has linked Harriet's disappearance to a number of gruesome murders from forty years ago, but it has become too dangerous to proceed alone. He needs a competent assistant, and he gets one: the gifted and conscience-free computer specialist, Lisbeth Salander. This truculent young woman has problems of her own. She in unwilling to take orders, rides a motorbike like a Hell's Angel and handles makeshift weapons with a skill born of rage.

This improbably pair unravel a dark and appalling family history. But the Vangers are a secretive clan, and Blomkvist and Salander are about to find out just how far they are prepared to go to protect themselves.