During the conflict with the Disciples of Ragnos–a Sith cult dedicated to the resurrection of the Sith Lord Marka Ragnos, Jedi Master Luke Skywalker of the New Jedi Order sent Jedi Master Kyle Katarn and his apprentice Jaden Korr on a mission to Vjun to stop the Disciples of Ragnos from stealing the force energy from Bast Castle.
Following the capture of Rosh Penin by the Imperial Remnant, Jedi Master Luke Skywalker continued to send the members of the New Jedi Order out to various locations that could be targeted for dark side energy by the Disciples of Ragnos and the Remnant. He assigned Kyle Katarn and Jaden Korr to Vjun to investigate Bast Castle, one of Darth Vader's former strongholds.
Landing their ship, the Raven's Claw, in the vicinity of the castle, Katarn and Korr were immediately faced with the hazards of Vjun's acid rain. Using the Force to protect themselves, they came across Imperial Remnant hazard stormtroopers. After fending off the brutish soldiers, the two Jedi made their way through the canyons to the castle, fighting more Imperials as they went. At one point, after being pinned down by TIE Bombers, they discovered a nearby turbolaser. The two split up and made their way to the gun. Korr defeated a number of Imperials and Sith Cultists, but when he approached the doorway to the turbolaser, he encountered a Reborn, a dark side soldier last seen during Desann's attack on Yavin 4. After defeating the Reborn in lightsaber combat and destroying the TIE Bombers, Korr met back up with Katarn and they managed their way into the lower levels of Bast Castle.
Upon entering the lower levels of the castle, Katarn and Korr realized that the turbolift was turned off. Much to Katarn's chagrin, they had to enter the garbage pit in order to reach the upper levels of the castle. They ascended further up Bast Castle by destroying a number of electrical conduits and using them to get through a hole they created in the ceiling. After destroying a power generator to cut a path into the upper main hall, Katarn and Korr were separated yet again by the ensuing explosion. Katarn had fallen back to the lower levels, so he told Korr to move on first while he would try to catch up soon.
Battling more Imperials as well as assassin droids and droids armed with lightsabers, Korr eventually came to one of the main chambers of the castle, which held the toppled remains of a statue of Darth Vader. Battling more New Reborn, Korr knew he was getting close to something.
Upon entering the meditation chamber room, where the Cultists were draining the dark side energy of the castle, Korr encountered Rosh Penin and the Kothos twins. Thinking that Penin was being held prisoner, Korr urged Penin to come with him, but that was not the case. Penin, noticeably more somber, revealed to Korr that he had turned to the dark side and joined the Disciples of Ragnos. Korr was then forced to engage in a duel with his friend. Korr seemed to be the more advanced fighter, however, Penin would be constantly rejuvenated with energy transferred to him by the Kothos twins. Korr changed tactics and slew the twins first before taking Penin down. Korr stood over his friend as Katarn entered the room. Just then, Tavion Axmis appeared and revealed herself as Penin's new master and leader of the Disciples of Ragnos. Pinning Katarn against a pillar with Force lightning and holding Korr down, Axmis gloated over Katarn and taunted him for sparing her in their last duel. When Korr threw his lightsaber at the ceiling to cause it to collapse and break the stalemate, Axmis destroyed his lightsaber with Ragnos's scepter and fled with Penin. While Katarn used the Force to temporarily prevent the ceiling from falling, Korr used Katarn's lightsaber to cut a hole in the floor and they jumped through it to a lower level. After getting free, they searched the castle for Axmis and Penin but could not find them, so they returned to Yavin 4.
Back at the Jedi Academy on Yavin 4, Katarn and Korr informed Skywalker about what happened on Vjun. For displaying bravery and skill in defeating the three Dark Jedi, Korr was promoted to the rank of Jedi Knight and allowed to build a new lightsaber to replace the one he lost. Katarn also sensed Korr's growing anger toward Penin's betrayal, and warned him that it could lead him to the dark side.
- The New Essential Chronology