Game Of Thrones fans will be able to "return to Westeros this year" after author George RR Martin announced a prequel to his series of novels.
It is set "300 years before A Game Of Thrones", when "dragons ruled Westeros".
On his blog, Martin said he was "thrilled" that a "monumental history of the Targaryen kings of Westeros" would be published on 20 November.
Called Fire And Blood, it is a "hefty book, almost 1,000 manuscript pages" and "illustrated throughout".
He added, playfully, that he had "seen the archmaester's manuscript".
Martin wrote: "Since it was handwritten on vellum with a quill pen, he required my help in transcribing the text to a more modern format: WordStar 4.0, on a DOS computer."
The blog also contains news that fans may find disappointing: the long-awaited sixth volume in the Game Of Thrones series, The Winds Of Winter, will not be arriving this year.
"No, winter is not coming… not in 2018, at least," Martin said. The fifth volume, A Dance With Dragons, was released in 2011.
The new book, which Martin describes as an "imaginary history" and "not a novel", will enable readers to "return to Westeros this year".
Blogging about the prequel, Martin said: "This first volume covers all the Targaryen kings from Aegon I (the Conquerer) to the regency of Aegon III (the Dragonbane), along with their wives, wars, siblings, children, friends, rivals, laws, travels, and sundry other matters.
"For those not up on your Westerosi history, that's Aegon I, Aenys, Maegor the Cruel, Jaehaerys I (the Conciliator), Viserys I, Aegon II (and Rhaenyra), and Aegon III (the regency).
"Oh, and there are dragons too. Lotsof dragons."
There had to be a second volume, Martin said, because "the story doesn't end with the regents of Aegon III. There is a lot more history to come."
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He ends his blog post by saying: "Archmaester Gyldayn is hanging up his quill for a while.
"As for me, I'm returning once again to THE WINDS OF WINTER."