During the Cold War, a venture to Megalox Beta was executed by Commander Poe Dameron and the Resistance's Black Squadron. Their objective was to find Lor San Tekka. The intention was to interrogate Grakkus, a Hutt crime lord held captive, who had an encounter with Lor San Tekka in the past. The First Order Agent Terex's presence complicated the Resistance's undertaking. Grakkus proposed to share the information with the first individual to liberate him; consequently, Poe directed BB-8 alongside other astromech droids to deactivate the prison's gravity field, thereby subjecting Terex and the inmates to the planet's intense gravity. Following Grakkus' liberation, the Resistance acquired additional details regarding Lor San Tekka's location, however, they paused the search to address a spy who was leaking information to the First Order.
Commander Poe Dameron of Black Squadron discovered during the mission to Ovanis that Grakkus, a Hutt crime lord, had once met the explorer Lor San Tekka. Grakkus had been incarcerated since the Age of the Empire within the formidable Megalox prison situated on the planet Megalox Beta. Megalox Beta featured intense gravity, and the prison was safeguarded by a gravity field, shielding the inmates from the planet's powerful gravitational pull. General Leia Organa successfully bribed Luta, the prison's Warden, to permit Poe and Black Squadron to enter the facility.
Nevertheless, the First Order had been informed about Black Squadron's impending visit via a spy. They deployed Agent Terex, an adversary Black Squadron had previously faced, to extract the information from Grakkus. Terex also bribed Warden Luta and her guards into abandoning Poe and his team inside the prison instead of escorting them to Grakkus' fortress. Poe, along with his Black Squadron comrades Temmin Wexley, Karé Kun, L'ulo L'ampar, and Jessika Pava, journeyed to Megalox Beta aboard their starfighters. Following their reception by Warden Luta, they disembarked, leaving their ships and droids at the space station orbiting the prison.
Black Squadron was accompanied by several prison guards aboard a shuttle that landed in a hangar. Upon arrival, the guards deserted Poe and his team, revealing the conspiracy. Unable to sway the guards with a million credits, Black Squadron resolved to battle their way through the mass of prisoners. Employing a gas and setting their blasters to stun, Black Squadron succeeded in fighting their way to Grakkus' fortress. Upon reaching their destination, they were confronted by Grakkus and his entourage of Hutts, who possessed mechanical enhancements to their bodies.
Acknowledging Poe's accomplishments, Grakkus granted him an audience but disclosed the presence of another visitor, Agent Terex. Aware of the Resistance's and First Order's vested interest in his knowledge concerning Lor San Tekka, Grakkus reneged on his agreement with Terex and proposed to divulge the information to whoever facilitated his escape first. Seeking vengeance against Grakkus, Terex convened with the imprisoned crime lords Papa Toren, Kan Be, and Isin. In exchange for aiding their escape, he persuaded them to mobilize their gangs for an assault on Grakkus' compound. Grakkus instructed the gangsters to kill Grakkus, Poe, and his fellow pilots.
Aiming to gain an advantage over Grakkus and Terex, Poe instructed BB-8 and the other astromech droids O-R10N, R2-HA, and R4 to disable the space station's gravity field. After subduing several guards, the droids managed to access the control chamber. However, they were attacked by a security droid which destroyed O-R10N. Meanwhile, Black Squadron joined forces with the Hutts to defend the fortress from the mob's onslaught. Following a struggle, BB-8 managed to electrocute the security droid, allowing the astromech droids to proceed with their mission.
After BB-8 and the droids disabled the gravity field, Poe and his fellow pilots donned gravity belts. The full onslaught of Megalox's gravity overwhelmed Terex and the gangsters. Papa Toren wept after one of his Ximpi was killed by the heavy gravity. Meanwhile, Poe and his comrades managed to free Grakkus. Poe then contacted Warden Luta and confronted her over her betrayal. He offered to give her back control of the prison if she allowed Black Squadron to escape with Grakkus.
Terex summoned his ship Carrion Spike and got one of his droids to evacuate him. Since the crime bosses had failed in their mission, he abandoned them to die. Returning to the space station's hangar, Black Squadron and Grakkus reunited with their droids minus Jess's droid O-R10N . They then departed in their starfighters with Grakkus following in a shuttle. Before leaving, BB-8 restored control of the prison back to Warden Luta. However, a vengeful Terex rammed through the space station with his ship Carrion Spike, disabling the gravity shield for good.
Warden Luta dispatched shuttles to evacuate the prisoners but they were attacked by the Carrion Spike. Despite Grakkus' objections, Temmin convinced Poe to turn Black Squadron around and they attacked Terex's ship. With the Carrion Spike sustaining heavy damage to its systems, Terex was forced to cloak the ship and retreat into hyperspace.
Following the dogfight, Grakkus disclosed information on the worlds that Lor San Tekka to Poe in return for Black Squadron running hyperspace calculations for him. Poe shared this information with General Organa after returning to the Resistance base on D'Qar. Dameron wanted to continue with the search for the explorer but General Organa told him to investigate how the First Order had been able to obtain information on their operations. Meanwhile, Agent Terex was reprimanded by Captain Phasma for failing to transmit the data he had been sent to obtain. When she ordered him to return to First Order Space for a debriefing, Terex switched off the hologram and decided to delay his return.
Eventually, Poe was able to resume his pursuit of Lor San Tekka. He discovered that Tekka had retired to Tuanul village on Jakku. Lor San Tekka presented Poe with a map leading to Luke Skywalker, asserting that it would "set things right." Shortly thereafter, Tuanul village endured an attack by the First Order, resulting in Poe's capture. However, BB-8 managed to escape with the map to the Resistance with the help of the disillusioned stormtrooper Finn, the scavenger Rey, and the smuggler Han Solo. As a consequence of these occurrences, the First Order initiated its conflict against the New Republic and the Resistance.