The Non-Canon Expert looks at what Darth Vader understood about Darth Plagueis outside of the scene between Jedi Knight Anakin Skywalker and Supreme Chancellor Palpatine in Episode 3: Revenge of the Sith, explaining how the Legends lore reveals Darth Vader’s knowledge of the connection between Palpatine and Plagueis and whether Palpatine revealed significant details about Plagueis to Vader during the Imperial era. This is a Legends story for Darth Vader, Palpatine, and Darth Plagueis with information found within the Episode 3: Revenge of the Sith novelization, «Star Wars: Death Star,» «Star Wars: Dark Lord: The Rise of Darth Vader,» and the Book of Sith reference book.