While most of the Jedi Order died during the execution of Order 66, some Jedi had even more horrifying fates. In the third episode of Star Wars Rebels, “Rise of the Old Masters,” the crew of the Ghost learn that the Empire is holding Jedi Master Luminara Unduli captive in an Imperial prison. The team goes to free her and discovers the Luminara's horrifying fate.
Early in the episode, the crew of the Ghost hears a transmission from Gall Trayvis, an exiled Imperial Senator and supposed ally of the Rebellion who later is exposed as an Imperial agent working to bring Rebels to their doom. In the transmission, Trayvis declares that Jedi Master Luminara is alive and imprisoned in the Stygian system. Trayvis demands the Empire grant Luminara a trial before the transmission is cut off. Footage of Luminara in prison clothes being escorted by Stormtroopers makes the message appear even more authentic.
Kanan Jarrus and the rest of the Ghost's crew make it their mission to free Luminara, and Kanan also wants to have Ezra Bridger train with her instead. Ezra's training with Kanan has not been going well, and this decision exacerbates the problem. Ezra believes that Kanan wants to get rid of him. Instead, Kanan is insecure about his teaching ability and wants to be reunited with another survivor of the Order.
When the crew arrives at the prison, Kana can sense Luminara, but her presence is "clouded." After Kanan and Ezra locate her cell, they find her sitting sadly and silently, and Kanan can tell that something is not right. The image of Luminara walks over to a sarcophagus in the wall, revealing the truth -- Luminara has been dead all along.
At that moment, the Grand Inquisitor arrives. He explains that Luminara died much earlier, but "her bones continue to serve the Empire, luring the last Jedi to their ends." This fate is particularly cruel for multiple reasons. Luminara was very focused on the importance of letting go and accepting death -- both of allies and of oneself -- when the time comes. This led to her clashing with Anakin Skywalker in Star Wars: The Clone Wars when their Padawans were presumed lost. The Empire will not let her go and let her bones rest. Instead, they weaponize the remaining Jedi's hope to find more survivors of the Order to lure them to their doom.
Luckily, the crew of the Ghost escape and plan to warn other Rebels about Luminara’s demise, ensuring that no other Jedi are slaughtered trying to save her. This episode serves as a turning point in Star Wars: Rebels; at the end, Kanan renews his commitment to training Ezra, and the two become closer. The episode also sets up the Grand Inquisitor as a cruel, credible threat, proving just how alone Kanan Jarrus and the rest of the surviving Jedi are in the new Imperial Order. With the trap's reveal, Luminara may finally be able to rest, but the weaponization of her bones still shows that the Empire will go to horrifying lengths to eradicate the Jedi and solidify the Emperor's hold on the galaxy.