The hunt for Darth Sidious was a mission that the Jedi Order undertook to locate and apprehend the Sith Lord that eluded the Galactic Republic for over a decade. The effort started on Cato Neimoidia after the battle there alerted the Jedi to a mechno-chair that provided the Jedi a chance to locate the Sith Lord. The mechno-chair also enabled for the Jedi to follow a trail that led them to the Sith's lair in the abandoned LiMerge Building in Coruscant's industrial district.
But Sidious himself soon became aware that the Jedi were attempting to hunt him down and decided to use that to his advantage. He ordered his apprentice Count Dooku to divert the Jedi investigation and to kill two loose ends that could have further led the Jedi to him. These efforts failed and the Jedi Masters Mace Windu and Shaak Ti managed to begin investigating the LiMerge Building. But Sidious prepared for this and with General Grievous coordinated a sudden attack on Coruscant in order to throw the Jedi off his scent. This venture succeeded in part: the Jedi were diverted but Aurek Team engaged Sidious and his droid forces. Sidious revealed his face to one officer before the latter died from his injuries. This ended the investigation into Sidious and preserved his secret leading Grand Master Yoda to believe that Sidious fled offworld.
The Sith Order revealed themselves to the Jedi Order first on Tatooine and then on Naboo in 32 BBY but in the decade after remained silent and did not return to prominence as the Jedi suspected would be the case. In this time, the Order questioned whether the Sith Lord killed on Naboo had been a master or an apprentice, and debated the possibility of a so-called "Second Sith". Count Dooku - himself revealed to be a Sith Lord - revealed to the captured Jedi Knight Obi-Wan Kenobi on Geonosis in 22 BBY that a Sith named Darth Sidious held influence over several senators in the Galactic Senate; it was the first such time that the Jedi learnt about Sidious in name.
The Jedi were unable to secure further information on Sidious throughout the Clone Wars despite their suspicions that the "Second Sith" could be someone in the inner circle advising the Supreme Chancellor, with such people as Sate Pestage and Mas Amedda as possible suspects.
In the last month before the war ended the Galactic Republic secured a much-needed win on Cato Neimoidia but failed in their attempt to capture the Trade Federation leaders Nute Gunray and Rune Haako. But this failure became a greater success in the sense that the Republic managed to secure a mechno-chair that gave them their first glimpse of Darth Sidious himself. The Jedi High Council decided that the time had come to find and capture the elusive Sith Lord and believed that the mechno-chair was the first positive step in that direction.
The Council dispatched Jedi Master Obi-Wan Kenobi and Jedi Knight Anakin Skywalker to follow clues that could lead them to Sidious and decided at first to keep the investigation a Jedi affair without reporting it to the Supreme Chancellor. But the battle at Belderone prompted Grand Master Yoda and Mace Windu to inform Palpatine about their investigation. Palpatine - as Sidious - summoned his apprentice Count Dooku to Coruscant where the pair discussed the Jedi's initiative. Sidious tasked Dooku with diverting the Jedi however possible to keep them off his trail while also ordering him to take care of those loose ends that could lead the Jedi to him and to their hidden base.
Kenobi and Skywalker arrived on Charros IV to meet the Xi Char with the former Trade Federation protocol droid TC-16 (captured on Cato Neimoidia) in tow to act as a translator. The purpose to their visit was to question the Xi Char about engravings that were found on the mechno-chair belonging to a certain Xi Charrian named t'laalak-s'lalak-t'th'ak. He answered the questions put to him but became nervous and attempted to flee. The commotion sees the Jedi chase the Xi Charrian through a warehouse which caused major disruptions before he was caught. He answered their questions while the Xi Charrian prelate arrived and demanded that Kenobi and Skywalker leave due to the disruptions caused. The Jedi learnt that the chair came to Charros IV from Escarte.
The Jedi arrived at Escarte but the authorities there were denied the chance to land. But Skywalker harassed the patrol ships to land to the point where a tractor beam guided their ship to the landing platform. The base's captain arrived to arrest them but en route reveals that he is the Republic Intelligence agent Travale. Kenobi and Skywalker are thrown into a cell with the Bith Thal K'sar (the one who worked on the chair) but Travale's cover is blown and he too is incarcerated.
But Travale manages to cause a power failure that enables the four to escape. Kenobi and Travale go to deactivate the tractor beam to allow their ship to leave the planet while Skywalker and K'sar get to the ship. Skywalker further interrogates K'sar who revealed there were two chairs and that the one he worked on in 33 BBY contained a hyperwave transceiver and a holoprojector. K'sar elaborated that Darth Sidious himself contacted him and once the chair was completed never heard from the Sith Lord again. It was at that stage that K'sar realized that his recent death sentence was Sidious attempting to cover up his tracks. K'sar also told Skywalker that the chair he worked on ended up on an experimental craft and told them that the Jedi could find the pilot in hiding on Naos III.
Darth Sidious hoped to set up a trap on Naos III and instructed Dooku to hire assassins to kill Fa'ale Leh and Kenobi also. The Jedi arrived on the planet and searched several cantinas looking for a trace of Leh. The two managed to locate the Lethan who assumed the name "Genne" in order to escape those pursuing her since she revealed to the Jedi that those who worked on the ship were all killed off not long after she delivered the ship to the client. Leh was aware that K'sar was the sole survivor besides herself.
But assassins cornered the three before she could answer additional questions. Leh's right lek was lost during the escape but she managed to tell the Jedi that she delivered the ship to a building in Coruscant's industrial district. Leh also told them that she delivered it to someone who looked like a Jedi but was not because their lightsaber was different.
The failure on Naos III prompted Sidious to order General Grievous to accelerate their plans to attack Coruscant as the last-ditch attempt to divert the Jedi. He likewise instructed Dooku to act as bait on Tythe to divert Skywalker and Kenobi while he would deal with those hunting him down on Coruscant.
Mace Windu and Shaak Ti led Aurek Team and several Padawans into the LiMerge Building with Captain Dyne leading the investigation. His assessment of the building confirmed that Dooku met with Sidious in the building and it led the group to a turbolift that in turn led them to tunnels leading them towards the direction of the Senate District. Examining those tunnels led them to a repulsorlift speeder bike that would lead them to 500 Republica but a sudden jolt in the building forced the Jedi to leave to investigate and to learn that Coruscant was under attack. The clones continued their search and found a door in the tunnel with one sentient behind it and droids as well.
The following commotion saw the entire team slain save for Dyne who in his final moments looked upon Sidious to see that he was in fact Supreme Chancellor Palpatine.
Palpatine duels Mace Windu after it is revealed the former is Darth Sidious.
The Jedi failed to locate and capture the Dark Lord and the clones that picked up the search beneath Coruscant were killed in the attempt to apprehend the Sith Lord. The Council believed that Sidious fled offworld but did not learn until around a week later that Sidious was in fact Supreme Chancellor Palpatine. This revelation led to a Jedi attempt to arrest the Sith Lord; the four Jedi were each slain and the Dark Lord succeeded in his decade-long plan to convert Anakin Skywalker to the dark side as his third Sith apprentice Darth Vader.