The Girl in the Spider's Web: Book 4

Then Blomkvist is contacted by renowned Swedish scientist Professor Balder. Warned that his life is in danger, but more concerned for his son's well-being, Balder wants Millennium to publish his story - and it is a terrifying one.
More interesting to Blomkvist than Balder's world-leading advances in Artificial Intelligence is his connection with a certain female superhacker.
It seems that Salander, like Balder, is a target of ruthless cyber gangsters - and a violent criminal conspiracy that will very soon bring terror to the snowbound streets of Stockholm, to the Millennium team, and to Blomkvist and Salander themselves.