The quest known as the Mission to Queyta saw five Jedi Masters embark on a journey to find a cure for the chemical weapon called swamp gas. This weapon had been used to annihilate the Gungan population on Ohma-D'un. The Jedi group consisted of Obi-Wan Kenobi along with four Jedi who roamed the galaxy: the Bothan Knol Ven'nari, the enigmatic Jon Antilles, the celebrated liberator of enslaved individuals Nico Diath, and the venerable Jedi master Fay. Their pursuit of the antidote led them to the volcanic planet Queyta, where a Separatist chemical production plant, nestled within the lava flows, was responsible for manufacturing the weapon.
However, the Separatist military leader, Count Dooku, dispatched his Dark Acolyte Asajj Ventress and the notorious bounty hunter Durge with orders to also secure the antidote. The factory was staffed by Skakoans wearing specialized pressurized suits. Durge exploited these suits to trigger a massive explosion, resulting in Master Ven'nari's death. The explosion destabilized the entire complex, and Master Diath perished in the lava after being overwhelmed by molten rock falling from the collapsing ceiling. Antilles sought revenge by engaging Durge, allowing Kenobi and Fay to pursue Ventress. Durge, however, overpowered the Jedi and cast him into the rising lava.
Fay and Kenobi confronted Ventress and successfully obtained the antidote. As they tried to escape the collapsing facility, Ventress retaliated by fatally impaling Fay from behind with her dual lightsabers before fleeing in Durge's vessel. In her last moments, Fay transferred her remaining energy to Kenobi, enabling him to escape the sinking complex with the antidote just in time.
Upon hearing reports of the Ohma-D'un tragedy, the Jedi issued orders to discover the source of the chemical weapon. Obi-Wan Kenobi, having witnessed the Gungan colony's destruction firsthand, investigated the new danger, uncovering a clandestine Separatist chemical factory situated on the lava-covered world of Queyta. Kenobi was joined by four Jedi Masters known for their nomadic lifestyles: Knol Ven'nari, Nico Diath, Fay, and Jon Antilles—all considered legends and some of the greatest Masters of the Jedi Order.
Despite feeling inadequate among such esteemed Masters, Obi-Wan was reassured by Fay that his experience with the swamp gas would be invaluable to their mission. The Jedi quickly found the chemical plant, a mobile structure that moved along the lava flow. After getting inside, the Jedi encountered many battle droids and Skakoan guards and workers in specialized suits. Before long, a much greater threat appeared in the form of Separatist Commander Asajj Ventress and the Gen'Dai mercenary Durge.
The battle for the antidote commenced when Durge opened fire on the Skakoan workers, his shots puncturing their pressure suits and causing a massive explosion inside the plant. Master Ven'nari used her Force powers to absorb the fireball's energy, but she sacrificed her own life in the process. Jon Antilles engaged Ventress as she attempted to reach the antidote, but he was defeated when Durge destroyed the bridge he was standing on.
Though Antilles survived his fall, Nico Diath was not as fortunate. Ventress weakened the ceiling supports above him, causing molten lava to rain down on the Jedi Master. He fell from the walkway into the lava below. Antilles retaliated by attacking Durge, but the massive Gen'Dai proved too strong. Antilles was thrown into the lava, but he managed to melt the regenerative thug's arms before he died.
Now the only Jedi survivors, Obi-Wan and Fay confronted Ventress, with Fay sending shards of metal flying at the Dark Jedi. Ventress fell, but she recovered while Durge distracted the Jedi. An explosion sent Fay spinning to the ground, where Asajj impaled the Jedi Master on her twin lightsaber blades.
Despite the destruction they had caused, Ventress and Durge did not kill Obi-Wan, though Ventress vowed to kill him the next time they met. Fay gave the weakening Obi-Wan the last of her strength to make a leap to safe ground with the antidote.
Obi-Wan Kenobi, wounded and distraught, succeeded in flying his Jedi starfighter back to the Jedi Temple on Coruscant with the antidote. However, the incident had left him disoriented and he crashed his starfighter into the landing platform during the landing, nearly killing his apprentice Anakin Skywalker and Master Mace Windu.
Kenobi was quickly rushed to medical aid, and eventually made a full recovery. A memorial service was held for the four fallen Jedi. Kenobi shared the story of their sacrifice with those attending the memorial, and expressed his distress over the death of Fay. Master Windu assured Kenobi that through her sacrifice, she had saved millions of innocent lives.
Sadly, the Galactic Republic had not seen the last of the deadly swamp gas. Unbeknownst to Obi-Wan, a second laboratory had been established on the far side of Queyta, and loaded its creations aboard the science vessel Gahenna. This vessel would travel the galaxy for the next two years, modifying the swamp gas weapon to become the Trihexalophine1138 toxin that devastated Honoghr.
The Jedi mission to recover the antidote from Queyta was initially presented in Republic 53. The New Essential Chronology later officially named the event "Mission to Queyta".