Lisbeth Salander is about to come crashing back into book lovers' lives in David Lagercrantz's hotly-awaited The Girl in the Spider's Web and, for the first time, some "key details" have been released.

The book is a continuation of the late Stieg Larsson's three Millennium novels - The Girl with the Dragon Tattoo, The Girl Who Played with Fire and The Girl Who Kicked the Hornets' Nest - and is due out on 27 August.

Lagercrantz, known for co-writing Swedish footballer Zlatan Ibrahimovic's autobiography, was authorised by Larsson's estate to write the novel, which he did on an internet-less computer before delivering the manuscrupt by hand to Swedish publisher Norstedts.

Troubled but fierce hacker Salander will be targeting the US National Security Agency in the new book, which picks up from where Larsson's last novel left off in 2009.

British publisher MacLehose Press has hinted that Salander and journalist Mikael Blomkvist "have not been in touch for some time" in Spider's Web, with the plot opening "as renowned Swedish scientist Professor Balder" asks Blomkivist to run his "terrifying" story about artificial intelligence.

It later becomes clear that Balder and Salander have joined forces, with Salander under attack by "ruthless cryber gangsters" known as the Spiders who will "very soon bring terror to the snowbound streets of Stockholm, to the Millennium team - and to Blomkvist and Salander themselves".

Lagercrantz said when Spider's Web was announced that he has stayed true to Larsson's writing style and has made use of the "vast mythology he left behind".