During the Battle of Ringo Vinda, CT-5385 (nicknamed "Tup") malfunctioned during battle and executed order 66 prematurely, killing Jedi General Tiplar. Following an initial examination of the Clone, the Republic sent him to a medical facility on Kamino in an attempt to discover the cause of this strange behavior. While there, Clone Trooper CT-5555 (nicknamed "Fives") located and removed a tumor from the head of Tup, in a desperate attempt to save his friend. However, immediately following the procedure, Tup died and Fives was placed under arrest by Jedi General Shaak Ti. Following the discovery of the tumor, Shaak Ti contacted Supreme Chancellor Palpatine to inform him of the discovery, the Chancellor ordered that the tumor be sent to the Grand Republic Medical Facility on Coruscant.
Following the conversation with Palpatine, Shaak Ti returned to the room where Fives was being held and commanded that the tumor be taken to the Jedi temple rather than the Grand Republic Medical Facility that the Chancellor had commanded it go to. Shaak Ti then told Fives that he would need to pass a final physical examination before he was sent back to the front. En route to the supposed examination, medical droid AZI-345211896246498721347 (otherwise known as AZI-3) revealed to him that he was actually going to have his memory wiped and be placed on sanitation detail on Kamino. Following this revelation, Fives swiftly disarmed the clones escorting him and escaped, along with AZI-3. After an alarm was sounded, Fives ran to the room in which he was being held prisoner and retrieved the tumor from a switched case.
Having retrieved the tumor, Fives quickly dashed to a hangar where he knocked out a clone pilot so that he could steal a ship. Just as Fives was entering the ship Shaak Ti arrived with several clone troopers. However, she was unable to stop Fives from stealing the ship. Having successfully stolen the ship, Fives set the ship on autopilot and - along with AZI-3 - jumped into the ocean below. After traveling back to Tipoca city on AZI-3, Fives re-entered the city and stole the armor of a passing clone trooper so he could fit in more easily. Fives then told AZI-3 to examine the tumor further. This led AZI-3 to take Fives to the genetic records hall where they could compare the DNA in the tumor to that of Jango Fett. AZI-3 then proceeded to compare the samples but found no similarity whatsoever. This discovery, led AZI-3 to believe that the tumor was, in fact, an implant rather than a natural brain tumor.
Seeking to discover whether the tumor was in him as well as Tup, Fives and AZI-3 fled again, this time to a medical chamber where AZI-3 performed a surgery on Fives to remove the tumor. Having discovered and removed the tumor from his brain, Fives wanted to discover how widespread the tumors were. At AZI-3's recommendation, they went to the facility where clones in the early stages of development were being grown. After examining several clone embryos, AZI-3 discovered that all clones had these tumors implanted in them from birth. At this point Doctor Nala Se entered the room after being alerted by two Kaminoans that Fives and AZI-3 had passed. Fives confronted her about the tumors in the clones to which Se responded that they were inhibitor chips designed to limit the aggressiveness that was present in Jango Fett. After this revelation, Shaak Ti and several Clone Troopers entered the room. Fives held Se at gunpoint. Following an exchange during which the evidence Fives had collected was presented to Shaak Ti, she ordered him and all the evidence to be taken immediately to Coruscant.
- Star Wars: The Clone Wars – "Fugitive" (First appearance)
- Star Wars: The Clone Wars – "Orders" (Appears in flashback(s))