Will the new season of Twin Peaks be based upon Mark Frost’s book, ‘The Secret History of Twin Peaks’, that came out last year?
As I understand it, the book is a “backstory”/prequel that fills the gaps between the ending of the last episode and the new season. Some things that are detailed in the book (like SPOILER Pete dying in the bank explosion, and Audrey being the only survivor) will be touched on in the show, but you do not need to read the book to enjoy the show.
Think of Mark’s book as the books that Lucasfilm/Disney are putting out for Star Wars… Whether it is “canonical” (part of the wiser story) or “expanded universe” (not necessarily “true”) we’ll see… David Lynch can potentially have something in the new season that contradicts something in the book.
But seeing as Mark wrote all the episodes as well as the book, I think that the book will be “canonical”.