Lisbeth Salander returns to Sweden after spending a year abroad. She soon finds herself accused of a triple murder when her fingerprints are discovered on the weapon used in the killings. The victims include prominent individuals connected to a sex trafficking operation. Journalist Mikael Blomkvist, who had been investigating the trafficking ring for months, believes that Lisbeth is being framed and begins his own investigation to find the real culprits and clear her name.

As Blomkvist digs deeper into the case, he uncovers connections between the murders and Lisbeth's troubled past, revealing a web of corruption and deceit involving powerful figures. Despite efforts from the police and criminals to silence them, both Lisbeth and Blomkvist race against time to bring the truth to light. Their separate quests converge, leading to shocking discoveries and setting the stage for a dramatic confrontation. The journey they embark on tests their resilience and unearths dark secrets that both would have preferred stayed buried.