"The Lost One" marks the tenth installment in the Star Wars: The Clone Wars television series' sixth season. This episode was initially broadcast on Super RTL, a German television network, on March 1, 2014. Subsequently, it became available in the United States and Canada through the streaming service Netflix on March 7, 2014.
"When a Jedi mission uncovers a lightsaber that once belonged to the deceased Master Sifo-Dyas, Yoda, Obi-Wan Kenobi, and Anakin Skywalker launch an investigation into his disappearance from a decade prior. This prompts Darth Sidious to instruct Darth Tyranus to eliminate any remaining clues that could potentially reveal the truth about the Sith conspiracy to the Jedi."
On the moon called Oba Diah, Plo Koon is investigating a signal originating from a Jedi's ship, a Jedi who had been considered lost for quite some time. Braving a powerful sandstorm, Plo locates the spacecraft and discovers the lightsaber that belonged to Sifo-Dyas. Plo relays this discovery to the Jedi High Council, where Yoda verifies that the lightsaber indeed belonged to Sifo-Dyas. Mace Windu points out that Sifo-Dyas was a council member before the Invasion of Naboo, but his proposals were deemed "too extreme" because he foresaw a Great Conflict and believed the Republic needed to establish an army. Obi-Wan Kenobi reminds everyone that during his pursuit of Jango Fett, he learned that Sifo-Dyas was the one who commissioned the creation of the clone troopers on Kamino. Yoda senses that there is more to this situation than meets the eye, and he is determined to uncover the truth.
Jocasta Nu reports that Sifo-Dyas supposedly died on Felucia during a diplomatic mission involving warring Jungle Felucian tribes. The details of the mission's conclusion were classified by the Supreme Chancellor's office. While Kenobi and Anakin Skywalker journey to Felucia, Yoda questions Chancellor Palpatine regarding the file, but Palpatine claims to have no knowledge of the Jedi Master and states that the file was handled by his predecessor, Finis Valorum, as he was still serving as a Senator at the time. Concurrently, Darth Sidious scolds Dooku for failing to address this "loose end" and uses a Force choke as a warning.
Before Yoda departs for Valorum, he learns that the Felucians cremated Sifo-Dyas' body and that another Jedi accompanied him. Valorum explains that Sifo-Dyas was dispatched to negotiate with the Pykes regarding an underground conflict. However, the negotiations were put on hold when Yoda instructed Sifo-Dyas to intervene in a dispute on Felucia. When questioned about the other Jedi, Valorum only mentions that his personal aide, Silman, accompanied Sifo-Dyas.
Anakin and Obi-Wan travel to Oba Diah to confront the Pyke Syndicate about the events surrounding Sifo-Dyas' death. Lom Pyke reveals that a man named Tyranus paid them to destroy the ship, and as collateral, Silman was held captive by the Pykes. After being imprisoned for approximately ten years, Silman has become mentally unstable. He warns that the Pykes are untrustworthy, but Dooku suddenly kills him before he can reveal the true identity of Sifo-Dyas' killer. Anakin and Obi-Wan engage Dooku in battle, during which Lom reveals that the man known as Tyranus is actually Count Dooku. Dooku then confirms to Obi-Wan that he had been truthful on Geonosis all along. Dooku murders Lom and briefly duels Anakin before overpowering him and escaping. On Coruscant, the Council infers that Dooku orchestrated the creation of the clone army. Wondering why their adversary would create an army for them, Yoda concludes that it must be the work of the Dark Lord of the Sith, and their only option is to "play his game."
The dialogue between Palpatine and Valorum implies that the episode occurs ten years after the events depicted in The Phantom Menace. However, Dooku's dialogue suggests that it takes place several years after the events of Attack of the Clones, which was also stated to be ten years after The Phantom Menace.
On Disney+, the episode is incorrectly titled "The Lost Ones."
