SPOILER WARNING: This article contains spoilers for "Rogue One: A Star Wars Story."
If you've seen "Rogue One: A Star Wars Story" already, then you know that it does a lot to reframe and explore the era surrounding the very first "Star Wars" film. It also features more of Darth Vader, showing him both in action and -- surprisingly -- in his version of "rest."
In a scene in the film, Director Krennic (Ben Mendelsohn) visits Vader in an ominous castle on a mysterious planet. The location of that planet and the purpose of that castle are left a mystery in the film but, thanks to comments from Lucasfilm representatives and the "Rogue One" companion books, we now have answers to the questions raised by that scene.
First, it's been confirmed that the planet is indeed Mustafar, the volcanic world featured in 2005's "Star Wars: Episode III - Revenge of the Sith." That's where Obi-Wan Kenobi and Anakin Skywalker's fateful duel was held, where Anakin lost his limbs and was gravely injured to the point where he needed life support armor to survive. The planet's inclusion was confirmed by Lucasfilm's Pablo Hidalgo on Twitter. The inclusion of Mustafar in "Rogue One" was apparently years in the making. Hidalgo confirmed on Twitter that the planet's inclusion in the season one finale of "Star Wars Rebels" was "designed to point to" "Rogue One."
Hidalgo's book "Star Wars: Rogue One: The Ultimate Visual Guide" also provides more information on Vader's castle:
Dark Monolith: Vader’s personal abode is an obsidian tower on an inhospitable world. It is the Emperor’s design that Vader lives in such an unforgiving environment. Vader’s attendant, Vanee, visits Vader as he meditates within a rejuvenation chamber. The stark, modern structure is built over an ancient castle full of dark secrets.
There's also more information specifically about the castle. In the "Art of Rogue One" book, screenwriter Gary Whitta says “the fact that he has chosen to build his mausoleum here is a nod to the conflict in him — that he would go back to this place to reflect on what happened to the man he once was. At the same time, it’s also terrifying, and when he emerges with all of his armor, he’s Darth Vader.” Additionally, the "Art of" book includes a note from production designer Doug Chiang that says the castle was "built over a natural cave — a Sith cave deep down below, in the lava world."
The castle comes from classic concept art from Ralph McQuarrie, who designed much of the look of the original "Star Wars" trilogy. The idea of Vader having a castle was originally conceived of by George Lucas while developing "The Empire Strikes Back." It didn't make it into that movie, but McQuarrie's concept art served as inspiration for "Rogue One."
Slash Film's research into the origins of Darth Vader's castle also indicate that the location could play a major role in a future "Star Wars" film -- even, possibly, "Episode VIII." A passage from the "Art of Rogue One" book hints at its future role:
Vader’s Mustafar castle in Rogue One would be concepted, designed, and explored beyond even the narrative needs of Rogue One itself. “We were building worlds, so we always had to keep in mind the broad strokes and the big picture, in case they were needed for the story,” said [Doug] Chiang.
"Rogue One: A Star Wars Story" is in theaters now.