The initial episode of the sixth season of the television program Star Wars: The Clone Wars, entitled "The Unknown," was initially broadcast on February 15, 2014 via the German television channel Super RTL. Later, on March 7, 2014, it was made available in both the US and Canada through the streaming service Netflix.
"A mysterious mental illness afflicts clone trooper Tup, leading to the unexpected and tragic death of a Jedi Master. Unable to explain his murderous actions, Tup is sedated and sent back to Kamino for examination. Anakin and ARC trooper Fives accompany Tup, but their return trip is ambushed by Separatists."
Anakin Skywalker, a Jedi Knight, along with twin Jedi Masters Tiplar and Tiplee, are leading several clone trooper units in an effort to reclaim the ring space station orbiting Ringo Vinda's orbit. They are facing off against the occupying droid force commanded by Admiral Trench. Among the clone forces are Clone Captain Rex, ARC trooper Fives, and clone trooper Tup. Recently, Tup has been experiencing odd mental episodes that cause him to become briefly disoriented. As the Jedi and clone forces advance into the station's command center, Tup suddenly enters a trance-like state, repeatedly uttering, "Good soldiers follow orders." Spotting Tiplar during one of these blackouts, Tup unexpectedly approaches her and kills her by shooting her in the head with a blaster. This unpredicted assault throws off the battle's progress and the composure of the Republic troops, forcing them into retreat.
Tup undergoes medical evaluations, but surprisingly, no explanations are found for his strange condition, which causes him to oscillate between trances and periods of lucidity where he has no recollection of his blackouts. Suspecting a Separatist conspiracy behind this irrational behavior, Anakin decides to send Tup back to Kamino for a more in-depth examination. Tiplee suggests that the breakdown might be attributed to a rumored anti-clone virus allegedly developed by the Separatists. Trench, having also observed the clone's peculiar disorder, contacts Count Dooku. Initially, Dooku assumes the clone simply betrayed the Jedi, but when Trench clarifies that the clone seemed to be in some kind of trance, Dooku grows concerned. He then reaches out to his Sith Master, Darth Sidious, concluding that Tup's behavior could prematurely expose their true plans for the war, leading the two Sith to decide to capture the clone before the Republic can analyze him.
The Republic arranges for a Rho-class transport shuttle to transport Tup to Kamino, with Fives promising to share a drink with him upon his return. As the transport departs the space station and prepares to jump to hyperspace, one of the pilots detects an approaching contact. A HMP droid gunship accompanied by five B2 super rocket troopers ambushes the convoy. The rocket troopers neutralize the escorting fighters, while the gunship launches a discord missile, and the resulting buzz droids eliminate both pilots, though one manages to transmit a distress signal before being killed. The clones guarding Tup quickly realize they are under attack and arm themselves to defend Tup. While one of the medical officers manages to eliminate two of the super battle droids, all of the clones are eventually killed. The remaining droids then release Tup from the medical table and place him in a container before returning to Separatist territory.
After inspecting the shuttle's wreckage, Skywalker, Rex, and Fives promptly realize Tup is missing and deduce that his strange illness is of significant interest to the Separatists. Tracking the signal from Tup's communicator, they stealthily make their way to the ring station's main hangar just as Tup is being loaded onto a shuttle, but find it too heavily guarded to engage in a direct assault. However, just as the shuttle is about to depart the hangar, Fives comes up with the idea to use grappling lines to hitch a ride on the shuttle as it leaves the hangar. Subsequently, the three board the ship, incapacitate the droid crew, and return to their grappling lines to await another transport to Kamino. Fives convinces Rex to let him accompany the transport, and the two, along with their afflicted comrade, head for Kamino.
The episode showcased a redesigned version of the B2-RP super battle droids, as well as the B2 super rocket trooper, which bore a resemblance to the female Zentraedi power armor featured in the animated series Robotech.
Despite the transport used to carry Tup to Kamino being referred to as a "medical frigate," its design in the episode was that of a Republic frigate.