Star Wars The Clone Wars: Season 6, Episode 10

6 - 10: The Lost One

A Jedi mission finds a lightsaber belonging to the long-dead Master Sifo-Dyas, prompting Yoda, Obi-Wan Kenobi and Anakin Skywalker to being an investigation into his decade-old disappearance. This sparks Darth Sidious to order Darth Tyranus to clean up any loose ends that may lead the Jedi to discover the truth of the Sith conspiracy.