This mission occurred some time after the events of the Battle of Yavin. Luke reluctantly underwent the mission after an Imperial transport capsule was identified to have crash landed on the planet. What began as a mission to investigate the capsule eventually ended up getting more complicated upon the revelation that the transport capsule, along similar capsules, had ties not only to an outbreak of the highly contagious and deadly Bledsoe's disease, but also to various attacks on Rebel bases by the Empire shortly thereafter. Eventually, Luke and an assigned Rebel contact, a female Ogemian named Anduvil, managed to to find out the connection between these events while Luke ended up infected with Bledsoe's disease, and promptly destroyed the primary Imperial base, capturing its commander to ensure their escape from the planet.
During the Galactic Civil War, the Galactic Empire frequently sent various space pods to the worlds of Rebel Sympathizers, which led to both an outbreak of the Bledsoe's disease, and later the destruction of several Rebel outposts. Likewise, because of the destruction of the Death Star, the Imperial forces also managed to gain a stronghold over the planet as well as constructing a base on Tatooine. An Imperial transport capsule containing Bledsoe's disease infected Squill meat was later sent to Tatooine, with the plan being to recover the transport capsule and presumably sell it to Mos Eisley to infect the populace and then glean into the star eyes and then quarantine them. However, the impact of the capsule caused a tremor strong enough to wake a pack of Jawas with them recovering the capsule, beating the Imperials to it, and also believing that they got a free snack for the road. Two stormtroopers found the crash site, but reported back to base that they haven't found any sign of the capsule until one of them noticed the Sandcrawler tracks and deduced that they won't be able to find any sign of the capsule in the future, either. They grew concerned, as that would mean that by the time they locate the Jawas and their corpses, their eyes would be unreadable.
A short while later, the Rebel Alliance received a report of a capsule crash landing on Tatooine via observers at Anchor-Head, and issued an order to Luke Skywalker: To abandon his reconnaissance mission and head to Tatooine immediately, as the situation was a "Code Grave." Luke initially was glad to get an assignment outside of the reconnaissance mission due to not gaining any leads until he learned of where he was supposed to go. Luke, having bad memories of his life on the planet, demanded they send someone else to Tatooine as he was unwilling to return to the planet, and stated that he'd need a very good reason for returning to Tatooine. Learning about the transport capsule, as well as the Jawas taking it before either the Empire or the Rebels could get their hands on it, as well as suspecting that it contained information vital to the Rebel Alliance's survival, Luke, C-3PO and R2-D2 ended up entering hyperspace en-route to Tatooine. Upon exiting hyperspace in the Tatooine system, he got a message from an anonymous female requesting that he not reply to the message, but rather go directly to Mos Eisley's cantina upon landing and request for Anduvil of Ogem. Luke ponders whether she was an Alliance contact or if she's luring him into a trap.
Upon landing at Mos Eisley spaceport, Luke is shocked at the increase in size of the spaceport, a large amount of traffic, as well as the increased presence of Imperials. He left C-3PO and R2-D2 outside of the Cantina, suspecting that they still had the no droids policy. Upon entering, Luke experienced a flashback to when he first entered the cantina, although his inattentiveness nearly got him killed by a bounty hunter under Jabba the Hutt's employ, who was hired as a hit on Skywalker due to a grudge. However, the bounty hunter ended up shot in the arm by a female patron. The female patron then identified herself as Anduvil of Ogem, and arranged for two Red Dwarfs to be ordered for the corner table, also citing that the Ogems joined the rebellion as the Empire's "credits were overcharged" compared to the Rebellion "paying in cash." Anduvil then briefed him on the situation: Contrary to what Luke initially believed, the mission entailed more than simply an investigation of a crashed transport capsule — it was cracking an intelligence operation against the Empire to find out the connection between the capsules, the outbreak of Bledsoe's disease on various Rebel-sympathizing worlds, and various Rebel outposts end up destroyed by the Empire shortly thereafter. Aduyil was personally involved in the mission largely due to the capsules and Bledsoe's disease killing her father, and thus forcing her to take over the family business as her family had no male heir.
Suddenly, one of the Jawas that discovered the transport capsule unexpectedly dropped dead after drinking a beverage, with one of the bartenders also discovering that the Jawa's cause of death was from Bledsoe's disease. Realizing that they had little time before they potentially ended up infected, especially in a place as crowded as Mos Eisley, Anduvil immediately grabbed Luke and bolted, also ordering Luke not to breathe. After picking up R2-D2 and C-3PO (who were moved to a waiting area a slight distance away from the catina due to a surly security droid), they rushed out of Mos Eisley. They eventually managed to escape to within Tatooine Desert, and Luke then proceeded to guide her to Obi Wan's hut in the Jundland Wastes. Unfortunately, shortly after arrival, they were ambushed by Tusken Raiders. They managed to wipe out the Tuskens, but not before their speeder ended up trashed by them. Luckily, they left their Banthas behind. Luke and Anduvil then took the Banthas. By dawn the next day, they arrived at their destination, but they also found something else: A run-down Sandcrawler, several dead Jawas, and Imperial stormtroopers inspecting the dead bodies. Luke was also baffled as to why the stormtroopers would be inspecting the Jawas, especially their eyes, when their manner of death was obvious, until Anduvil explained that Bledsoe's disease also resulted in the eyes of the infected victim to possess stars in their eyes. Although they don't know the reasons why they'd need to inspect their eyes to find something, it was clear to them that they couldn't find whatever it was they were looking for. The Stormtrooper search team, deducing that the Jawas don't possess "windows" in their eyes, reported back to base and then promptly shot the deceased Jawas to cremate them.
Luke decided to investigate the Sandcrawler to find any evidence connecting the pod, the Bledsoe's disease, and the Rebel attacks, even though a fusioncutter all but ensures that no Bledsoe's disease outbreaks are inside. Unexpectedly, Luke ended up bitten by a diseased Squill, and they ended up caught by the stormtroopers. Anduvil explained the situation to the stormtrooper, knowing that they would take them to the base and thus learn more about what was going on. However, a stormtrooper noticed that one side of Luke was odd, and then discovered that he had slight discoloration in his eyes, but hadn't gotten "window-eyes" yet. The stormtroopers then took them into custody to bring them to their base, but they left C-3PO and R2-D2 behind near the abandoned Sandcrawler. C-3PO has mixed thoughts on the stormtrooper's treatment, although R2-D2 suggests they pilot the Sandcrawler. Upon arrival at the Imperial base, they immediately issued Luke to a medical chamber. Anduvil apologized to Luke, stating that it was the only way to get in the base and thus get closer to finding out the truth, but then she interrupted herself in shock at Luke's eyes: Although Luke's vision itself was fine, they were filled with stars. Afterwards, the base's medical officer, Dr. Kaaldar, then does an ocular print, but then orders for him and Aduyil to be quarantined, stating that the window effects contain secrets for the Empire and thus cannot allow him to live, although he does promise that if the window effects wear off before death, he'll supply the serum to save his life. However, Luke suddenly cuts down a stormtrooper, stating that he'll survive whether it suits the Imperial's interests or not, although he ends up collapsing from dizziness. Anduvil then pointed a gun at Kaaldar and ordered him to administer the serum, as well as explain everything he knew about Bledsoe's disease and the Empire's connection to it. After administering the serum to Luke, Kaaldar then explained that the Empire used Bledsoe's disease for a two-fold purpose: to crush any chances of rebellion on Rebel-sympathetic worlds, and to locate the Rebel Alliance's secret bases. He explains that they managed to trace the secret bases via the window-effect of the infected victim's eyes. In other words, the eyes of someone infected with Bledsoe's disease contained star maps for the Imperials to use to garner the locations of the secret Rebel bases. He also stated that the strand itself was also genetically modified to act as a code, and noted its effectiveness. Luke then tells him that the only reason that his plan worked was because no one survived the Empire's scheme until he did. Luke then approached the doctor, with the latter demanding he not get any closer as the cure hasn't gone into effect yet. The base's alarms then go off, baffling Luke as there weren't supposed to be Rebels in close proximity.
Meanwhile, C-3PO and R2-D2 managed to reactivate the Sandcrawler and arrive at the Imperial base with the intention of rescuing Luke and Anduvil. Unfortunately, they didn't come up with a plan beyond barging through the wall, due to C-3PO not being a strategist, and thus ended up captured after the Sandcrawler's treads were snapped and the stormtroopers burst open the entrance to the Sandcrawler. The commander then ordered for the Sandcrawler to be put back in the desert, and for the droids to be disposed of. Luke, having overheard this, attacked and grabbed the Imperial commander, demanding that he cancel the order, and also warned him that he was still infected with Bledsoe's disease. Meanwhile, Anduvil, intending to find a more practical method of aiding Skywalker before he ends up disintegrated, infiltrated a TIE/ln Starfighter hangar and proceeded to sabotage the engine of a TIE by misaligning an energizer. She then rushed to a speeder. Luke then warned the commander that even if he is cured of Bledsoe's disease, the stormtroopers' blasters aren't curable, before demanding once again for the commander to rescind his order. However, the commander, preferring to die loyal to the Empire than abandon his orders, gave the order for the Stormtroopers to fire on them. However, the Stormtroopers ended up disintegrated from various explosions before Anduvil arrived in a stolen speeder, picked up Luke, C-3PO, R2-D2, and the captured commander and departed from the base before the base detonated from the sabotaged fighter engine.
With the base destroyed, they arrived back at the Mos Eisley Spaceport, and used Luke's starship (with Aduyil tagging along due to her own starship being confiscated by the Empire), also bringing the Imperial commander along in order to ensure that they leave the planet unscathed. Luke himself expressed relief that he can finally leave Tatooine again.
3PO later told the events of the mission to the supercomputer Mistress Mnemos, when tasked with recording the early missions of Luke and his allies.