Co-Chief of State Jacen Solo sent a detachment of Galactic Alliance Guard personnel, led by Major Salle Serpa, to the Jedi Academy on Ossus. The academy at this time was occupied mainly by Apprentices because most Knights were on Coruscant at the Funeral of Mara Jade Skywalker. Because of rising tensions between him and the Jedi Order, Jacen sent the GAG troopers to threaten the Jedi into compliance.
Jaina Solo, Zekk, and Jagged Fel came to Ossus to find Alema Rar, but they barely found any traces of her on the planet. They did find one trace of her though, which led them to land in the Jedi Academy's hangar. Jaina and Jag went into the academy while Zekk stayed in the Ossus forest. When the two entered the academy, they found it deserted. Jaina thought that maybe Kam and Tionne Solusar stopped lessons for the day in order to honor Mara, but this wasn't the case. They went up to flight control, but what they found surprised them. They found GAG troopers controlling it, led by Major Salle Serpa. Jaina realized that Jacen was holding the academy hostage, but according to Serpa, the GAG troopers were sent to make sure that the Jedi and the Galactic Alliance stay friends. He also assured the two that Alema Rar was not on the planet. Serpa then threatened the young ones in order to convince Jaina to stay so she wouldn't be able to tell anyone what was happening. He also made the two surrender their weapons so they wouldn't pose a threat against the academy. Zekk stayed hidden in the forest by the academy to give information to Jaina and Jag, and to get information from them. Also, he stayed there in case he needed to surprise the GAG troopers if they actually attacked the Jedi.
Since Jaina and Jag had to stay at the academy, they had to temporarily call off their hunt for Alema. Jaina lived with some of the youngest students at the academy and she acted as their dorm parent. Jag on the other hand helped out with supervising the teenagers. As long as the academy stayed orderly the children were left to the adults, while Serpa concentrated on planetary security. Things were going well enough that classes started again. One early morning though, Jaina realized that something bad was happening to the academy and its students.
One very early morning, about two weeks after Jaina and Jag arrived at the academy, Serpa was ordered by Jacen to use coma gas to knock out the adult Jedi. The gas caused Jaina to stay in a deep sleep, but soon she heard Ben Skywalker's voice and the voices of scared children, which made her wake up. Although she was awake, Jaina's eyes wouldn't open so she had to rely on the Force. Jaina was able to pull herself together and through the Force she was able to sense a GAG trooper spraying the coma gas into her dormitory room. She used the Force to throw the GAG trooper into the wall outside her door and he went into unconsciousness. She used the Force again to open up her door and fresh air immediately rushed into her room. Once she had fresh oxygen in her lungs, she left her room finding her dormitory empty of all young ones. She looked outside the dormitory door and saw all of the young ones and Padawans being herded to the Central Exercise Pavilion by GAG troopers.
Serpa directed the groups of young ones and apprentices in a specific way. He arranged them by alternating groups of taller children with groups of shorter ones, segregating them with GAG troopers. When all of the organizing was done, Serpa selected specific Jedi, having them form a circle around him in the pavilion. He ordered them by gender, species, and height. When Tionne Solusar saw what he was doing, she marched to the pavilion angrily, in order to stop Serpa from doing anything that would harm the young ones. Tionne told him to return the Jedi to their beds and he would be forgiven for his bad timing, but Serpa took this as a threat and shot her leg.
At this point, Jaina had had enough of what was happening. Jag was able to get to her dormitory, and he informed her that there were snipers located around the dormitories and that they were waiting for the adult Jedi to come out of their dormitories to shoot them. Jaina decided that they needed to take out the snipers quickly and quietly. The two left the dorm and Jaina found two snipers hiding behind a bush. She was able to distract them, making them look into the opposite direction, so she could approach them from behind. She then was able to snap their necks, killing them. She took one of the rifles, but while she was doing this, another shot was fired at Tionne, and Tionne couldn't help but howl in pain. This caused Kam Solusar to start to get angrier and angrier.
Jaina jumped onto the roof of her building so she could kill the two snipers up there, but she was too late. Jaina heard another shot being fired and Kam Solusar took Serpa's bait. He ran out of his dorm, and was shot three times by one of the snipers on the roof. Jaina quickly killed both snipers, dropped over the roof's edge, and saw Tionne curled up at Serpa's feet, without the lower parts of one of her legs and one of her arms. This, combined with Serpa calling Jaina and Jag cowards for not showing themselves, caused Jaina to start firing at the GAG troopers. She gave the signal to the young ones and they turned on the troopers. The Jedi used the force to confuse and injure the GAG troopers, and the older Padawans were even fighting hand-to-hand combat with the troopers. Jaina knew she had to stop Serpa, so she ran to him in order to capture him. As she ran she saw young ones on the ground with blaster burns. Jaina reached Serpa and told him to surrender, which he did not. Serpa was about to shoot Jaina, but Zekk came out of nowhere, lightsaber in hand, and he severed Serpa's arm. Serpa knew he had to surrender and Jaina, Zekk, and Jag captured him and the rest of the GAG troopers, most of whom were appalled by Serpa's orders.
Zekk and Jag stayed on Ossus to wait for more Jedi Knights while Jaina headed to Kashyyyk. When she got there she told Luke, what had happened. Neither Luke, Jaina or any of the Jedi could believe that Jacen would do something like this. This, combined with Jacen's actions of burning the Kashyyyk forests and torturing Ben, led Luke to ask Jedi Master Kyp Durron to devise a plan that would help tracking the fallen Jedi's movements.
The apprentices would later be moved to a secret base on the Sanctuary Moon of Endor.