Fired from the National Security Agency, Frans Balder recruits hacker Lisbeth Salander to steal FireWall, a computer program that can access codes for nuclear weapons worldwide. The download soon draws attention from an NSA agent who traces the activity to Stockholm. Further problems arise when Russian thugs take Lisbeth's laptop and kidnap a math whiz who can make FireWall work. Now, Lisbeth and an unlikely ally must race against time to save the boy and recover the codes to avert disaster.