MS-133 was an Imperial science group, operating under the authority of Moff Kentor Sarne, the warlord controlling the Kathol sector within the Outer Rim Territories. Doctor Lancer Brunou, a well-regarded archaeologist, headed the team, which consisted of scientists, technicians, and soldiers. In 8 ABY, their mission was to investigate extensive ruins on the planet Aaris III, remnants of an ancient civilization dating back thousands of years. After several months of work, the team located a chamber called the Place of Kastays and discovered the Plaque of Victory, an artifact. This Plaque, a sentient but inanimate entity, triggered the civil war that destroyed Aaris society by instilling paranoia and homicidal urges in those nearby.
Following this discovery, MS-133 members began to feel like they were being watched from the surrounding jungle. The situation deteriorated as team members started disappearing, and the base camp was attacked almost every night by the primitive descendants of the original Aaris inhabitants. Ultimately, only Doctor Brunou and a research assistant, Solla Deremot, survived. They were rescued by the FarStar, a CR90 corvette from the New Republic, which was tracking Sarne in the Kathol sector. The Plaque, brought aboard the FarStar, began to affect the corvette's crew in a similar way, until it was ejected through an airlock.

In 8 ABY, Moff Kentor Sarne, the Imperial warlord who governed the Kathol sector of the Outer Rim, commissioned the formation of MS-133. The team's purpose was to investigate a series of large ruins located on the planet Aaris III. These ruins suggested the presence of an ancient civilization that had vanished thousands of years ago. Sarne's intention was for the team to uncover the cause of the planet's population extinction. MS-133's personnel were selected from the scientific, technical, and military elements of his forces, and the entire operation was placed under the leadership of Doctor Lancer Brunou, a renowned archaeologist affiliated with the University of Byblos. The mission's classification was top-secret.
The team, which also included a small contingent of soldiers and technicians, traveled to Aaris III using a Curich-class shuttle. Once in orbit, a communications booster satellite was deployed, and upon landing, the team established their base camp in a vast field of ruins. Doctor Brunou suspected, but couldn't confirm, that the pilot of the shuttle—who was also the commanding officer of the security detail—had specific instructions to land at those precise coordinates. Regardless, MS-133 commenced their explorations, with Brunou documenting their progress in a journal as they mapped and excavated the ruins. On the expedition's forty-ninth day, one of the team's scientists, Grigor Tansad, discovered an entrance into one of the ruined metal structures. This structure was situated away from the main base camp, closer to the shuttle's landing site. Brunou authorized the establishment of a secondary base camp, manned by Tansad, another scientist named Jelok, two technicians, and five troopers.
While examining a chamber inside the ruins, Jelok noticed that the walls were adorned with square, orderly bas-relief pictographs that produced sounds when touched. Jelok believed these sounds held the key to understanding the language of the long-gone civilization, while Tansad theorized that they represented a dating system. Both scientists began working on translations until Tansad successfully demonstrated his theory by correlating the sounds with Aaris III's orbital period. Following this breakthrough, Jelok abandoned his own efforts and assisted Tansad. A day later, Jelok, together with research assistant Solla Deremot, discovered a flat metal ingot inside a sealed vault in the chamber's floor. Brunou studied the new find at the primary base camp and determined that it was composed of a metal unknown to Imperial science. Furthermore, the object emitted faint traces of energy. Brunou decided to send the discovery back to Moff Sarne's capital, Kal'Shebbol, for more detailed analysis in a well-equipped laboratory. Unbeknownst to the team, the ancient Aaris—the civilization that had once inhabited Aaris III—knew the ingot as the Plaque of Victory. The Plaque was an inanimate sentient entity that sustained itself by feeding on the life force of other beings. Its ultimate goal was to trigger destruction by inducing fear, paranoia, and violent behavior in individuals, causing them to turn against each other. It was in this manner that it had instigated the Aaris civil war.

After the Plaque's discovery, several troopers began experiencing unease, reporting the sensation of being watched from the jungle, despite the lack of evidence of intelligent life on the planet. The team remained completely unaware that the Aaris had survived their civilization's collapse and that their primitive descendants still dwelled within the ruins of their former cities. The commanding lieutenant led a group of five soldiers into the dense foliage to investigate. After an hour, the team back at the base camp heard blaster fire coming from the jungle; none of the reconnaissance team returned. The remaining troopers immediately distributed sidearms to the science and technical personnel. Jelok and Tansad continued their work in the chamber—now known as the Place of Kastays thanks to Tansad's translation work on the pictographs—although Tansad began to suspect that something was amiss with Jelok, attributing his behavior to professional jealousy. Tansad's translations had revealed the Plaque of Victory's role in the Aaris' downfall and how one individual—the scholar Kastays—had documented the final days of his people through the pictographs.
That night, the Aaris launched an attack on the base camp from the jungle. The remaining troopers returned fire, but both a technician and Doctor Theda sustained injuries. Upon inspecting the edge of the jungle in the morning, the bodies of several troopers who had entered the jungle the previous day were discovered. Jelok later reported that Tansad was missing and that two technicians had been shot by energy weapons fired from the jungle. Doctor Brunou, defying Sarne's standing orders, ordered an immediate evacuation of the planet. He instructed Jelok to pack up the secondary camp; when the scientist refused, insisting that his work was at a critical stage, Brunou ordered some troopers to escort him to the shuttle while the base camp was being packed up. That night, the team's shuttle was destroyed, and the remaining members of the team at the base camp—Brunou, Deremot, the injured Theda, two troopers, and a technician—began fortifying one of the mounds in the ruins, erecting makeshift barricades and fortifications, and mounting an E-Web heavy repeating blaster on the ramparts. Again defying Sarne's orders, Doctor Brunou transmitted a distress signal to Kal'Shebbol, requesting assistance. Two days later, the base camp was attacked again. The two troopers and the technician charged over the barricades to engage the Aaris, leaving Brunou, Deremot, and the increasingly ill Theda.
Brunou's transmission was received, but not by Moff Sarne or any of his forces. During the months that the team had been on Aaris III, Kal'Shebbol had fallen to the New Republic. Sarne had since retreated into the depths of the Kathol sector with the remnants of his military. The New Republic, in an attempt to locate him, had assigned the CR90 corvette FarStar to track his movements. It was the FarStar that intercepted the distress call, and the commanding officer, Captain Kaiya Adrimetrum, rerouted the ship to respond, hoping that the team might possess valuable information regarding Sarne's whereabouts. A landing party was dispatched to rescue the survivors; Deremot and Brunou were initially suspicious of the team, believing them to be allied with the Aaris—whom they had never clearly seen and were still unaware of their survival—but eventually, the New Republic personnel managed to convince them of their good intentions. Brunou and Deremot were evacuated to the FarStar, but Theda had already died.

Aboard the FarStar, Brunou and Deremot shared all the information they had regarding the expedition and Sarne's reasons for sending them to Aaris III. Adrimetrum decided to send a second landing party to the planet to gather supplies and fresh food. Both survivors of MS-133 refused to return to the surface. The landing party also investigated the events that had occurred on the surface. They discovered Grigor Tansad's body in the pictograph chamber, hidden beneath rubble, clearly killed by a blow to the head with a large rock found nearby. The remains of the shuttle also revealed traces of detonite, indicating its use in the shuttle's destruction.
While in orbit, the crew of the FarStar began to experience the sensation of being watched, similar to what MS-133 had felt on Aaris III's surface. This was because Brunou had brought the Plaque of Victory aboard. He and Deremot argued over ownership of the artifact, which escalated into a physical altercation witnessed by several crew members. Eventually, the crew realized that they were under the influence of an external force and deduced that the artifact Brunou had brought aboard was the cause. They managed to take the artifact from the scientists and eject it through one of the corvette's airlocks, thus ending the Plaque's influence over them.

MS-133 was composed of individuals with backgrounds in science, technology, and the military. Doctor Lancer Brunou, a respected archaeologist from the University of Byblos, led the team. The scientific team also included Doctor Theda, Grigor Tansad, and Jelok, with Solla Deremot—whose primary scientific focus was biological research—serving as a research assistant. The scientists were supported by at least three technicians, as well as a squad of ten troopers, including their commanding officer, who also served as the team's shuttle pilot.
MS-133 was created for the adventure Artifact of Aaris in The DarkStryder Campaign, published by West End Games. In the adventure, the player-controlled crew of the FarStar, a New Republic ship, responds to the team's distress signal. Most of the team is either dead or missing before the start of the adventure, and the remaining members—Lancer Brunou and Solla Deremot—can die during the adventure depending on the gamemaster's decisions and the players' actions. If the characters survive, they can join the crew of the FarStar. Deremot will willingly ally herself with the crew and be pleased that her talents are being put to good use, as she had no affection for the Empire. Brunou, on the other hand, is a staunch Imperialist and will seek to abandon ship and rejoin Sarne's forces at the earliest opportunity.
Artifact of Aaris suggests that, under the Plaque of Victory's influence, the members of MS-133 turned against each other, resulting in multiple deaths and the destruction of the shuttle. However, The Complete Star Wars Encyclopedia, published in 2008, confirmed that the team was attacked by the remnants of the Aaris civilization.