The Undervaults of Gwongdeen were a high-security storage facility located on the planet Gwongdeen. The Kaminoan scientist Kolac Pru stored a sample of thornsuckle plant in a safety-deposit box in the Undervaults, and his former assistant, Mahjo Reeloo, vowed to destroy it. She hired the smugglers Han Solo and Chewbacca to take her to the Undervaults in the Millennium Falcon, first stopping on Dhandu 3 to steal a key to an adjacent deposit box owned by Jayyar Lu-wehs. Once at the Undervaults, she placed a in Lu-wehs' storage box, but learned Pru had already retrieved the deadly plant and planned to clone it for the Mandragonian Mob.