Mission to the Prism The mission to the Prism occurred in 19 BBY after the rise of the New Order and the subsequent coup by General Gentis . The coup was an attempt to assassinate Emperor Palpatine , Darth Vader , and many other Imperials in an attempt to end the tide of senseless deaths . Gentis managed to take over Coruscant by faking terrorist attacks , one of which used the poisonous gas Aorth - 6 . This gas wiped out dozens of loyal Imperials and soldiers , and it was only through the dark side of the Force that Palpatine managed to survive . Severely weakened , Palpatine was taken by Darth Vader , Moff Trachta , and Lieutenant Laurita Tohm to the hidden prison known as The Prism in the Diab system , where they believed they could revive the Emperor . Once there , Tohm devised a plan for retaking the capital by freeing the prisoners of the Prism . History . Prelude . In 19 BBY , a few weeks after the rise of the Galactic Empire , General Gentis attended a military meeting on Imperial Center . While seeking to escape the droning of the various Moffs , he discovered the Imperial Crematorium , and watched hundreds of dead Imperials be incinerated every minute . Realizing that even though the war had ended , the Emperor ' s warmongering ways would never cease , and he quickly set about seeking a way to end the senseless killing . A few months later , the cadets of six different academies from around the galaxy came to the capital in order to be part of the first graduating class of Imperial officers . Gentis , a hero of the Clone Wars , presided over the ceremonies . Laurita Tohm was the valedictorian of the Raithal Academy , and thus was given the rank of lieutenant by Gentis himself . Tohm was soon selected to be a part of Grand Moff Wilhuff Tarkin ' s fleet , but Gentis had other plans for the young officer . He ordered Ensigns Caul Gentis and Shens to keep Tohm " out of harm ' s way " . Tohm ' s friends locked him inside a prototype TIE / LN starfighter , and for a time , he assumed it was a practical joke . In reality , this was the first small step in Gentis ' s coup , as he believed that the promising officer would draw too much attention due to his prominence and deformities . Later that night , explosions rocked the cityscape for kilometers around , eliminating seventy - two Imperial targets within minutes . The officer ' s club , various Stormtrooper garrisons , the Comm Towers , and a supply depot were all destroyed . Imperial Plaza became ground zero in the battle that erupted , as " terrorist " forces swarmed through the city streets , fighting with the Empire ' s clone forces . The stormtroopers were losing the battle until Darth Vader appeared , rallying the troops and driving the enemy forces back . In the madness , Tohm had escaped from the prototype starfighter by engaging its ejector seat and landing in the midst of the battle . During the battle , Tohm came upon his wounded friend Shens . Shens begged him to kill Vader , but Tohm told his friend that he should have included him earlier , and shot Shens in the head . Tohm then bowed to Vader , who instantly respected his bravery and loyalty . As the pair made their way from the plaza , another explosion tore through the nearby buildings , unleashing a powerful necrotic virus known as Aorth - 6 . Dozens of Imperials , including Royal Guardsmen , were killed by the aerosolized virus , which liquified them from the inside out . Tohm donned a breathing device that he had taken from the TIE fighter when he ejected and followed Vader inside . There they found a mortally infected Palpatine and Moff Trachta . Palpatine was using the dark side of the Force to keep the virus at bay , but was losing the battle even with his formidable powers . Vader accused Trachta of being in league with the conspiracy , but the Moff vehemently denied it , saying they needed to get the Emperor into hiding ; fear of his power was the only thing keeping the Empire together . The trio escorted Palpatine to secret hangar below the Imperial Palace , where they loaded him aboard a stealth transport . The Ghost Prison . Once safe , Trachta revealed that Gentis had pretended to want to meet the Emperor in order to present his most prized students , but instead unleashed the virus . He then attempted to kill Tohm , saying he didn ' t trust him , but Vader knocked the blaster from his hand . The three discussed where they could possibly go to hide the Emperor , and Tohm stated that Gentis ' s influence would likely have overtaken all three Rims . Vader then remembered of a place he had once heard of , but he needed more information , and took Lieutenant Tohm to the Jedi Temple in order to get it . While they were gone , Gentis ' s engineers sent a command to every droid within five kilometers to kill any Imperial officer they saw . Aboard the Emperor ' s shuttle , Trachta was attacked by a 2 - 1B surgical droid , while Vader and Tohm were attacked by lightsaber - wielding Jedi training droids . All three Imperials were victorious , however , and Vader led Tohm into the High Council Chamber and called up a holorecording of a Jedi Council meeting that Anakin Skywalker had attended . Skywalker demanded to know what happened to the myriad prisoners he had captured over the course of the war , but the Council told him that he was chasing rumors and nothing more . Skywalker persisted , saying that he would get the truth from Supreme Chancellor Palpatine , but Obi - Wan Kenobi calmed him , though Skywalker still left angry . The Jedi Masters further discussed the topic after Skywalker left , revealing that the secret prison was a tightly - kept secret , even from the Chancellor and the GAR . The Jedi believed that the Republic Security Force couldn ' t contain the Force - users , cyborgs , shape shifters and others that they had captured , and that once the war was over , they would then receive fair and open trials . Kenobi was displeased , but obeyed the Council ' s wishes , still asking that he be allowed to visit the prison himself . Master of the Order Mace Windu revealed the prison ' s location and urged Kenobi not to take Anakin . When Kenobi agreed , Vader flew into a rage , destroying the Council chambers and shouting that the Emperor had been right , that they had been plotting against the two of them from the beginning . He then urged Tohm to remember that the Jedi believed in too many ambiguities , when there was only the Empire , and everyone else . With their new information , the Imperials left for the Diab system , where the Prism was hidden . Over the course of the three day journey , Tohm attempted to connect with the Force , but Trachta discovered this and told him it would be unwise to discover any Force - sensitivity at that point . The two then recounted the tales of their mutual disfigurations to one another ; Trachta had been attacked by a Dark Jedi Padawan while Tohm was the victim of a Separatist attack that killed his family and maimed him . Trachta then remarked that traitors are only thus if they fail in their mission . Though the Imperials were confronted with a bewildered Jedi Master and a force of security droids , Vader cut down the Jedi and all three quickly dealt with the droids . They brought Palpatine to the prison ' s medical center , where they were able to staunch the disintegration of his body . Tohm then accessed the prison ' s databank , learning that there were two - hundred and eight prisoners held there , with over half for them arrested by Anakin Skywalker . Vader told Tohm that Skywalker was an impressive Jedi , but that he had killed him , and told Tohm to wipe the system clean . Trachta , however , wanted to find a particular prisoner , and had Tohm help him locate the individual . It turned out that the Padawan who had so terribly disfigured Trachta was imprisoned there , and the cyborg decided to spend several hours beating and torturing him to death . Knowing that there was no one they could trust to contact , Tohm devised a plan and asked Lord Vader for permission to undertake it : He wished to release all the prisoners of the Prism in order to form an army to take on Gentis . Prism riot . Lacking loyal or trustworthy soldiers , Tohm suggested to Vader that the prisoners of the Prism be released and allowed to fight for them , which would allow them to retake Coruscant from General Gentis . Vader amended Tohm ' s idea , and rather than simply releasing the prisoners , he forced 207 of them to fight one another , as well as Tohm and himself , for the right to serve the Galactic Empire . The battle was vicious and wild , with casualties mounting quickly . Separatist sniper Shonn Volta allied herself with Tohm after saving his life from General Ur ' Loach , while Vader defeated Nax Cirvan , a fallen Jedi , who then submitted to the Dark Lord . In the end , only thirty - three prisoners survived in fighting condition , including Volta and Cirvan . Vader ordered Trachta to tell the survivors what it meant to serve the Empire . Trachta told the survivors that their crimes were now forgotten , but their reasons for committing them were not — they would now serve an institution not beholden to the " selfish " senators of the Republic , nor the Jedi Order . The prisoners knelt before Trachta and the others , becoming Imperials through their submission .