The Secret History of Twin Peaks and Twin Peaks: The Final Dossier are both definitely very interesting reads and I'd highly recommend the both, but I'd add that they definitely come across more as Mark Frost's sole take on Twin Peaks, rather than Lynch's (much like how Fire Walk With Me was all Lynch, sans Frost). It's absolutely a valid take, but it is worth stating that the books do have a different flavor from (and some [very intentional] discrepancies with) the show. The books are much more rooted in "real world" history, myths, and belifs, and feel more tangible, almost like something akin to The X-Files-esque conspiracies than the total dream logic of the show and Lynch's work in general.
