A raid was attempted in 43.5 ABY by rogue Jedi Seff Hellin to free Jedi Knight Valin Horn from the Armand Isard Correctional Facility, a Galactic Alliance prison. The two Jedi were affected by the same psychosis—an illness that caused the affected being to believe that imposters had replaced everyone they knew except for other beings that suffered from the disease. Hellin hoped to free Horn, who had been encased in carbonite and placed in the prison. The Galactic Alliance hoped to capture Hellin, while Darkmeld—a covert organization formed by Knight Jaina Solo to counter Chief of State Natasi Daala's efforts to weaken the Jedi Order—hoped to capture the Jedi as well, in order to study the disease.
As his raid began, Hellin was attacked by two Darkmeld members—Imperial Remnant Head of State Jagged Fel and bounty hunter Tahiri Veila. He managed to defeat them, but the two attacked again, and Hellin was forced to abandon his goal. As he left the prison, Hellin was caught by Galactic Alliance bounty hunters Dhidal Nyz and Zilaash Kuh, who were serving in Daala's special-missions force. Solo, however, seized him from the bounty hunters and loaded him into a speeder piloted by Darkmeld affiliate Mirax Terrik Horn, Valin's mother. A speeder chase ensued, and the bounty hunters and several security speeders pursued them, but Darkmeld managed to shake off all of their pursuers. Hellin was taken to the Jedi Temple on the galactic capital Coruscant, where he was to be studied in secret by Mon Calamari Jedi healer Cilghal.
In 43.5 ABY, Jedi Knight Valin Horn suffered a psychotic breakdown induced by the dark side entity Abeloth, which caused him to believe that everyone he knew—except for other beings suffering from the same psychosis—had been replaced by impostors. Horn was kept in the Jedi Temple on the galactic capital of Coruscant, and after a brief rampage in his attempt to flee Coruscant, he was placed in the nearby Mon Mothma Memorial Medical Center instead; Horn's detainment there was a compromise to the Galactic Alliance government, which grew increasingly skeptical and controlling of the New Jedi Order under Chief of State Natasi Daala. The government soon froze Horn in carbonite kept him in Coruscant's Armand Isard Correctional Facility.
Rogue Jedi Seff Hellin, who suffered from the same disease, felt compelled to free Horn, as he believed that Horn was the only being he knew that had not been replaced by an impostor. Hellin was spotted outside the prison by the Force-sensitive Tahiri Veila, a member of Darkmeld—a secret organization formed by Jedi Knight Jaina Solo to counter Chief Daala's efforts to undermine the Jedi Order. Veila informed Solo of the sighting, and they instantly realized that Hellin's intention was to break Horn free. They also realized that if they could capture Hellin, they would be able to study the disease and potentially develop a cure for it.
Hellin created an intricate plan to enter and exit the prison undetected; a tunnel connected a law enforcement station with the prison to facilitate the quelling of prison riots, but Hellin burned a hole in the permacrete above for access, leaving the side that led to the prison sealed. As a last-minute addition, Solo and Imperial Remnant Head of State Jagged Fel decided to include Mirax Horn, Valin's mother, to their group of conspirators in order to make use of her contacts, skills, and funds. She would have to keep the group's existence hidden from her husband, Jedi Master Corran Horn, because the Jedi Council was not supposed to know of the organization so that—if they were ever questioned by the Galactic Alliance—they could answer truthfully that they knew nothing about Darkmeld.
A few days after securing his tunnel entrance, Hellin put his plan to free Horn into motion, but was swiftly intercepted by Veila and Fel upon entering the tunnel. Hellin believed Veila to be an impostor, and because of Fel's distinctive armor, Hellin thought Fel was a Mandalorian. Hellin attacked them, sending Fel flying backwards with the Force.
Hellin and Veila began a lightsaber duel, and Fel stood and shot a stun bolt at Hellin, who deflected the shot into Veila's leg. Next, Hellin turned and ran for a blast door that led into the prison and threw a thermal detonator at Veila. Fel picked up Veila and took off running down the tunnel. Hellin Force-pushed the detonator, keeping it rolling after them. When Fel and Veila were far enough away that Hellin believed the blast would not kill them—he had not come to kill imposters, merely to free Horn—Hellin triggered the detonator. Hellin knew that the blast would make the prison guards think that there had been a fuel explosion outside the prison, or that someone was trying to break free; so his entry would—at least, temporarily—remain a secret. Hellin then began to melt through the blast door with his lightsaber.
Fel's Mandalorian armor protected him and Veila from the blast, and Darkmeld member Winter Celchu called in to check on them. Fel informed her of the situation, and told Celchu to call the rest of Darkmeld to the prison.
As Hellin neared his goal, he was confronted by three security guards in a turbolift. He quickly incapacitated them and moved on, disabling holocams with the Force as he passed them. Hellin reached the room in which Horn was being kept and began to melt his way through the blast door with his lightsaber. Veila, however, was not far behind and reached the corridor outside the room. Veila began jumping up and down in front of one of the holocams in an attempt to draw all of the security guards to the area. Hellin quickly made it through the blast door and found the carbonite slab which held Valin Horn, but when he attempted to release Horn, an error code came up, setting off an alarm. Fel, whom Hellin still believed to be a Mandalorian, came through the door, and Hellin slashed at him with his lightsaber.
Hellin continued the attack, but Fel caught the blow on his impenetrable beskar crushgaunts. Veila entered the room as well, and as he realized that he would not be able to fight off his combatants and be able to free Horn, Hellin Force-threw the slab of carbonite containing Valin at Fel and Veila. Veila dodged it, but Fel was not quite quick enough to get out of the way, and he was hit by the slab and knocked aside. Hellin then ran out of the room, leaving the carbonite slab in the doorway to block the exit behind him. He ran down the corridor to the turbolift shaft and jumped blindly in, dropping a few meters. Luckily for Hellin, the lift was above him, and it slowed to a halt at the corridor which he had just left behind. Several security guards looking for Hellin took to the corridor, slowing down Fel and Veila's pursuit.
Hellin continued out through his escape route, returning to the tunnel he had used to enter the prison, when—as he passed by the place where his thermal detonator had exploded—he was cut off by more security troopers. He Force-flung the debris created by the detonator blast at the troopers and charged them, quickly incapacitating them. He then took a blaster rifle from one and a pistol from another. As he made for his escape, Celchu attempted to cut Hellin off, and Hellin quickly shot her with a stun bolt from the rifle. Sensing the presence of many security guards closing in around him, Hellin made a break for a shaft to the surface.
Outside the prison, Terrik Horn arrived in a speeder she had stolen from outside her family's suite. She spotted Hellin escaping and flew towards him, but was sideswiped by a cargo hauler piloted by bounty hunter Zilaash Kuh, who was working for Natasi Daala's special-missions force. Kuh's Quarren partner, inventor and bounty hunter Dhidal Nyz, fired an electric net at Hellin, who attempted to dodge the shot. The net, however, was too large. It wrapped about Hellin and immobilized him, sending paralyzing electrical surges through his body every few seconds. The connecting cable from the net to the gun went taut, and Hellin was yanked into the air behind the moving cargo hauler.
Solo arrived on the scene, having managed just minutes earlier to get away from Dab Hantaq, her Jedi supervisor—an agent that was tasked to keep track of a Jedi—and witnessed the bounty hunters' capture of Hellin. She contacted Terrik Horn—who was coming back around in her speeder—and told her to go after Hellin, who was being dragged along through the air. The cargo hauler passed over Solo, and she threw her lightsaber at the cable connecting the net to the gun and severed it. Hellin fell from the sky, still paralyzed by the electric net, and Solo slowed his fall with the Force, letting him hit the ground just hard enough to incapacitate him. Solo knocked Hellin out with a swift blow to his head with her lightsaber hilt. Terrik Horn quickly landed the speeder beside Solo, who lifted Hellin aboard and climbed in. The bounty hunters came around in pursuit, and four of the prison security's speeders took off after them. Not far behind, Veila and Fel—carrying with them the unconscious Celchu—quickly stole a speeder and joined the chase as well.
Five security speeders—one piloted by Veila—and the cargo hauler now followed Terrik Horn and Solo. Terrik Horn took the speeder into a tunnel used for maintenance and waste haulers, while Veila quickly maneuvered past two of the security speeders, passing just above the second one so that her speeder's repulsor wash knocked the security speeder into the wall. The security speeder crashed to the tunnel surface, and Veila piloted up underneath the bounty hunters' cargo hauler. Fel—fighting the hauler's repulsor wash—slowly stood up and began destroying servos and repulsor nozzles with his crushgaunts. At last, he found an auxiliary energy cell, which exploded as he squeezed it, peppering him with shrapnel. Smoke poured from the area, and the cargo hauler slowed, falling behind Veila's speeder.
Meanwhile, in the stolen speeder, Solo injected Hellin with a sedative. Turning back to the nearest pursuing security speeder, Solo Force-pushed it sideways into the tunnel wall, holding it there until the pilot was forced to decelerate and drop to the ground in order to keep control of the vehicle. She repeated this process twice more, until the only speeder remaining was that of Veila and Fel. Solo guided the group out of the maintenance tunnels to a small niche off of a major thoroughfare, where they parked the speeders.
After they parked, Celchu removed all forensic evidence from the two speeders so that they could not be traced back to any of them. Fel was returned to the Imperial Remnant embassy, while Veila, Terrik Horn, and Celchu met up with Tekli—a Chadra-Fan Jedi healer affiliated with Darkmeld—back in the Jedi Temple. They met up with Solo, who had checked in with Hantaq and was free of the supervisor once more, and Tekli opened up a special chamber which only she and fellow healer Master Cilghal were authorized to enter, strapping Hellin to a bed inside.
The next day, the raid was featured in the news. Suspicion fell upon the Jedi Order, but there was no hard evidence of the Jedi's involvement. Galactic Alliance Security forces, under the command of Captain Oric Harfard, arrived at the temple to take Hellin into custody, but since Solo had kept Darkmeld's actions secret from the Jedi Masters, acting Grand Master Kenth Hamner told them truthfully that he did not know where Hellin was. Terrik Horn and the non-Jedi members of Darkmeld also escaped scrutiny, as the only being who had been close enough to recognize any of them during the raid was Seff Hellin.
Later, Hantaq revealed to Solo that he had guessed that she had taken part in the raid, but had no proof, and so planned to do nothing about it. Deciding that Solo's plans were the right thing to do, Master Cilghal ran tests on Hellin in order to find out more about the disease from which he and Horn suffered.
The raid was created by author Aaron Allston for Fate of the Jedi: Outcast, the first novel in the Fate of the Jedi series, released in 2009.