A brief conflict occurred around the location of Pleem's Nexus circa 20 BBY. This conflict involved the Sith affiliated Nightbrothers Darth Maul and Savage Opress against a group of Jedi, their clone troopers, and other combatants.
After Darth Maul, Savage Opress, and the female captive departed from Orto Norwe, they journeyed to Pleem's Nexus to rendezvous with Esano. Their intention was to receive payment for the rescue of his sister. However, the Jedi who were pursuing them from Orto Norwe were closing in. Bruu Jun-Fan's psychometric skills allowed him to determine that the Sith were heading to Pleem's Nexus simply by "reading" the headband left behind by the captive.
Simultaneously, on Coruscant, Jedi Knight Anakin Skywalker was summoned back to assist in the pursuit of the two Sith. Before his departure, he informed Supreme Chancellor Palpatine that he would be unable to attend the Senate War Rally scheduled for that day, as he was to be involved in the capture of Darth Maul and his brother. Unbeknownst to Skywalker, Palpatine is secretly the Sith Lord Darth Sidious, who was Maul's former mentor. Palpatine, surprised to learn of Maul's survival, cautioned Skywalker to exercise care during the apprehension.
Upon arriving at Pleem's Nexus, Maul and Opress landed at Esano's palace. Esano's sister demanded that he provide the Sith with the promised reward for her rescue, threatening that they would kill her otherwise. Esano disregarded her plea, believing that her death would secure the family's wealth for him alone. Enraged, Maul launched an attack on Esano.
After Esano suggested that Maul and Opress should kill his sister, the two Sith initiated an assault on Esano, his sister's pet kerko, and his guards. The Sith quickly dispatched them, but Esano's sister was left unharmed. Maul declared that the palace now belonged to her, and in return, she provided them with the promised payment. Shortly thereafter, the Jedi strike team that had been tracking them arrived at Pleem's Nexus and landed at the palace.
Plo Koon, Bruu Jun-Fan, Ko Solok, and three clone troopers confronted the two Sith, brandishing their lightsabers and blasters. Plo Koon engaged Opress, while Jun-Fan and Solok focused on Maul, with the clones providing covering fire. Jun-Fan questioned Maul about his former master, stating that revealing his identity would lead to justice. However, this was not part of Maul's strategy, and he refused to disclose the identity of Darth Sidious.
During the engagement, Jun-Fan destroyed the container holding the reward intended for Maul and Opress. At one point, Opress employed The Force to push two of the clones off the landing platform, deflected a blaster shot at the remaining clone, and removed Plo Koon's breath mask. Plo Koon, incapacitated, could no longer participate in the fight and struggled to breathe. Separately, Maul threw his lightsaber at Jun-Fan, but Jun-Fan evaded the attack. Ko Solok, positioned behind Jun-Fan, was killed in the process. Enraged by Solok's death, Jun-Fan fought with increased aggression. Jun-Fan began to strangle Maul, but Maul used his mechanical legs to break free.
Just as Maul was about to defeat the Jedi Master, Anakin Skywalker and Obi-Wan Kenobi arrived in their starfighters and wounded Opress with the laser cannons. After landing, Maul and Opress escaped in their stolen starship, while Kenobi and Skywalker attended to Plo Koon and Bruu Jun-Fan.
Following Darth Maul and Opress's departure from the Pleem's Nexus system, Plo Koon recovered his breath mask and resumed breathing. He rushed to Bruu Jun-Fan's side and heard his last words before he passed away and became one with the Force. Skywalker, disheartened by the brothers' escape, was informed by Esano's sister that they had only escaped with their original ship and had left their reward behind. Maul, consumed by vengeance, continued his journey with his wounded brother into the unknown regions.