The Tatooine mission unfolded following the Battle of Yavin. Luke Skywalker, with reluctance, embarked on this mission after the detection of a crashed Imperial transport capsule on Tatooine. Initially intended as an investigation of the capsule, the mission grew more complex with the revelation that this capsule, and similar ones on other planets, triggered outbreaks of the extremely infectious and lethal Bledsoe's disease, quickly followed by assaults on nearby Rebel installations. Luke Skywalker, alongside Anduvil, a female Ogemite and Rebel contact, uncovered the link between these events when Luke contracted Bledsoe's disease. The Empire was deploying a genetically altered form of Bledsoe's to transmit coded intelligence about Rebel targets. After being cured, Luke, aided by Anduvil, obliterated the local Imperial garrison base, capturing its commanding officer to facilitate their escape from Tatooine.
During the Galactic Civil War, the Galactic Empire dispatched various transport capsules to planets inhabited by Rebel sympathizers. These capsules carried Squills infected with a genetically modified version of Bledsoe's disease, leading to widespread outbreaks. These outbreaks destabilized the social structures of planets suspected of supporting the Rebellion. Furthermore, the disease's specific genetic alterations caused discoloration in the eyes of the infected, which could be interpreted as star charts revealing the locations of hidden Rebel bases. Imperial forces then used this information to attack these bases. Concurrently, after the destruction of the Death Star, the Empire strengthened its control over Tatooine, constructing an Imperial garrison base. An Imperial transport capsule, containing infected Squills, was dispatched to Tatooine, intended for retrieval by Stormtroopers and subsequent infection of the local population. However, Jawas discovered the capsule first, thwarting the Empire's plan because Jawa eyes could not be read. Observers stationed at Anchorhead detected the capsule's crash and relayed this information to the Rebel Alliance.
Massassi One of the Rebel Alliance commanded a reluctant Luke Skywalker to abandon his ongoing space reconnaissance mission and proceed to Tatooine to investigate the capsule, classifying it as a Code Grave mission. Luke initially resisted returning to his home planet due to unpleasant memories, but eventually acquiesced, accompanied by C-3PO and R2-D2. Upon emerging from hyperspace, Luke received an enigmatic transmission directing him to Chalmun's Spaceport Cantina in Mos Eisley, and to a contact named Anduvil from Ogem. Luke quickly realized that the newly established Imperial base on Tatooine had significantly increased both traffic and military presence in Mos Eisley.
Chalmun's cantina continued to enforce its strict policy against droids, so Luke entered alone. He was nearly ambushed by a bounty hunter employed by Jabba Desilijic Tiure, but Anduvil intervened and saved him. She informed him that his mission extended beyond merely investigating a transport capsule; he was to unravel an Imperial intelligence operation and determine the connection between the crashed transport capsules, the outbreaks of Bledsoe's disease, and the attacks on Rebel bases. However, before Luke could gather more information, a Jawa within the cantina collapsed, indicating that the Bledsoe's outbreak had reached Mos Eisley.
Escaping the outbreak in Anduvil's landspeeder, Luke directed them to Ben Kenobi's hut to strategize their next move. They were ambushed by Tusken Raiders who destroyed Anduvil's Landspeeder, but after defeating the raiders, Luke and Anduvil commandeered their banthas. Anduvil led them to the Jawa sandcrawler that had initially discovered the transport capsule, only to find Imperial Stormtroopers scrutinizing the Jawa's eyes. However, Jawa eyes did not exhibit the discoloration associated with Bledsoe's disease, and the Stormtroopers eventually departed. While investigating the sandcrawler for an explanation of this peculiar behavior, Luke was bitten by a Squill. Anduvil regretfully informed him that Squills carry Bledsoe's disease, and that Luke was likely infected. Before Luke could formulate a plan, the Stormtroopers returned. Upon discovering that Luke had been bitten, the Stormtroopers apprehended them and transported them to the Imperial garrison base, leaving C-3PO and R2-D2 stranded in the desert.
At the base, Luke was handed over to Doctor Kaaldar, who determined that Luke's eyes had become discolored due to Bledsoe's disease, effectively transforming them into a star map. Luke and Anduvil realized that the Imperials were using genetically modified Bledsoe's to transmit coded messages and star charts to various worlds, secretly coordinating attacks on Rebel strongholds. Anduvil pleaded with Kaaldar to provide Luke with an antidote, but Kaaldar refused as long as Luke's eyes revealed the location of a secret Rebel base. Despite his weakened condition, Luke managed to overpower his captors and force Kaaldar to administer the antidote.
Outside the garrison base, C-3PO and R2-D2 had seized control of the abandoned sandcrawler and driven it through the main gate of the base. This successfully diverted the Stormtroopers' attention, but resulted in the droids' capture. While Luke Skywalker rushed to rescue them and took the Imperial commander hostage, Anduvil sabotaged the ion drives of the base's TIE Fighters. Luke, Anduvil, the droids, and the captured commander fled the base moments before the sabotaged ion drives exploded, obliterating the garrison base.
With the base destroyed, Luke, Anduvil, the droids, and their hostage returned to Mos Eisley. They utilized Luke's starship to escape the planet, using their hostage as insurance during their return to Yavin 4. They intended to compel the commander to disclose the details of the Empire's scheme, ensuring that Bledsoe's disease would no longer serve as a means of transmitting secret Imperial information.