The successful operation known as the Mission to Tawntoom was carried out to free Nilz and Auren Yomm from their captors. They had been abducted and transported to the fortress situated in the province of Tawntoom. Gaff's motive for taking Nilz was to compel him to treat Governor Bisad Koong, who had contracted the Rooze disease. Auren was seized as collateral to prevent Mungo Baobab from pursuing them. Nevertheless, Baobab located and liberated them both. Subsequent events led to the Galactic Empire's retreat from Roon and Koong's demise from the illness. Baobab and his companions then escaped aboard the Caravel.
After the skirmish that occurred in the Roon Sea, Mungo Baobab, along with his droid partners C-3PO and R2-D2, began preparations to leave Roon and return to Manda. Nilz and Auren Yomm guided the trio to the Pinnacles of Felth in search of the Rainbow Comets, hoping to map their journey home. However, at that very moment, Governor Bisad Koong, seeking to impress Admiral Terrinald Screed, unleashed the Rooze disease upon the Umboo province. This desperate act was an attempt to salvage his reputation after his previous failures (the lightstation, the games, and the Roon Sea). Tragically, Koong inadvertently infected himself and dispatched his chief lieutenant Gaff to retrieve Nilz Yomm, the only healer on Roon capable of providing treatment.
Gaff arrived at the Yomm residence while Nilz was attending to his infected wife, Bola. A scuffle ensued, and Auren was subdued. Gaff instructed the stormstroopers accompanying him to seize both Nilz and Auren, the latter serving as insurance against any rescue attempts by Baobab. However, before Auren could be taken away, Baobab secretly placed half of his memling on Auren's belt, intending to use it as a tracking device.
Aboard the cloudcraft, Baobab used the memling as a navigational tool to locate the Yomm's at the fortress in Tawntoom. He attempted to navigate the ship through a shortcut involving a volcano, but the intense lava caused them to crash into the snow on the far side of the cavern. A subsequent eruption triggered an avalanche, sending R2-D2 crashing into a mirror that was actually a molecular disruptor. This device drastically reduced the size of the astromech droid.
Baobab and C-3PO then managed to overpower two alien merchants using Baobab's seed launcher. They stole the merchants' robes to create a diversion for the guards at the entrance, while R2-D2 infiltrated the ventilation shaft to find the Yomm's. He successfully entered their cell, narrowly avoiding a sleeping Gaff and a goorl. After unlocking the cell, Nilz attempted to use the Rooze cure to incapacitate Gaff, but the attempt failed because Gaff, being a Kobak, was immune to the disease.
After reuniting with Baobab and C-3PO, the group of five attempted to board the Caravel, but Gaff intercepted them, arriving on a sandskimmer and alerting Screed and Koong. With the Yomm's safely on board the Caravel, Baobab and the droids hijacked Koong's aerial drilling platform. Baobab issued an ultimatum: he would surrender the cure and reveal the location of the Roonstones in exchange for Umboo being left unharmed. However, when the Roonstones were uncovered, Screed betrayed Koong, forcing the governor to take control of the drill. Koong accidentally sent all the Roonstones into the volcano, which in turn froze the fortress's only heat source, threatening to freeze the entire citadel. As Screed and his forces retreated from the planet, Baobab provided the cure to Koong before he and his allies fled. Unfortunately, it was too late for Koong, who perished as the fortress froze.
Baobab's time on Roon concluded with the mission to the fortress. However, while en route to Umboo, he discovered a single Roonstone inside R2-D2. Upon returning to Umboo, the cure was successfully administered to Bola and other infected individuals. Baobab instructed the droids to remain on Umboo until he returned from Manda, where he would update his father on his experiences on Roon.