"The Lost One" is the tenth episode of the sixth season of Star Wars: The Clone Wars. It is the hundred and eighteenth episode of the series overall. It premiered on March 7, 2014.
Official Description 
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A Jedi mission finds a lightsaber belonging to the long-dead Master Sifo-Dyas, prompting Yoda, Obi-Wan Kenobi, and Anakin Skywalker to begin 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.
