The Girl in the Spider's Web by David Lagercrantz was an excellent work of fiction as the fourth book in the Millennium Series started by Stieg Larsson with his books The Girl with the Dragon Tattoo, The Girl Who Played with Fire, and The Girl Who Kicked the Hornet's Nest.
Larsson died in 2004 and his family commissioned Lagercrantz to write another novel on the characters of Mikael Blomkvist and particularly Lisbeth Salander, with very enjoyable results.