The Girl in the Spider's Web by David Lagercrantz

Journalist Mikael Blomkvist receives a phone call from a source claiming to have information vital to the United States. The source has been in contact with a young female superhacker—a hacker resembling someone Blomkvist knows all too well. The implications are staggering. Blomkvist, in desperate need of a scoop for Millennium, turns to Lisbeth Salander for help. She, as usual, has her own agenda. The secret they are both chasing is at the center of a tangled web of spies, cybercriminals, and governments around the world, and someone is prepared to kill to protect it.