Mercy Mission " Mercy Mission " is the fifth episode of the . It aired on October 7 , 2011 . Publisher ' s summary . " " After groundquake s have devastated the planet Aleen , a Republic relief effort arrives , including the droid s R2 - D2 and C - 3PO . When the native Aleena ' s pleas go unheard , it becomes the duty of the droids to embark on a surreal journey through Aleen ' s subterranean world to save the planet . " " Plot summary . Senator Amidala and Master Yoda contact Commander Wolffe , the leader of the humanitarian relief expedition , for a status report on the situation on Aleen , which is fairly joyful considering the circumstances . A fully loaded relief force — including C - 3PO and R2 - D2 sent along as translators and to interface with the equipment — descends to the surface , which is planned to be only a brief stay because the troops would have to return to the war as soon as possible . The king of the Aleena , Manchucho , welcomes Wolffe and his troopers enthusiastically , though an aftershock disrupts the greeting somewhat . When C - 3PO tries to calm the startled villagers just as the quake stops , the Aleena view the golden droid as some sort of divine messenger and ask the Republic troops to put the earth to rest , a request Wolffe understandably has to pass . While Wolffe and C - 3PO explain the function of the delivered supplies to Manchucho , Boost , Sinker , and R2 - D2 enter the local Republican communication station to survey and repair the damage the quake has inflicted , accompanied by a few Aleena , who become increasingly impressed with the " magics " their helpers make work . When C - 3PO joins R2 in the station , the villagers are eager to show him something and lead the two droids to a collapsed structure , which contains a huge golden seal embedded in the ground . The seal is revealed to be the entrance of a tunnel leading into the subterranean regions of the planet ; when another quake hits the area , C - 3PO accidentally slips through the partly uncovered opening and plunges into the dark depths , followed by R2 . A tangle of branches cushions 3PO ' s fall , but then the rubble shaken loose from another shock clogs the entrance tunnel , trapping the droids underground . One of the Aleena tries to fetch help , but with no knowledge of their language Wolffe misunderstands their intentions , so Manchucho and a few of his people race to the structure and initiate a chanting ritual . While exploring the tunnels they have landed in , C - 3PO and R2 - D2 encounter speedy , sparkling lights chasing them and subsequently stumble into a strange subterranean ecosphere which is inhabited by sentient , tree - like beings called Kindalo , who demand they leave since they claim that the surface dwellers " destroy the peace . " After C - 3PO convinces them they bear the Kindalo no ill will and mentions that they are here to help with the earthquakes , the Kindalo send the droids to Orphne , an amphibian - like humanoid with mystical powers . Orphne explains that a mutual balance has existed between the Aleena and the subterranean world , which was supposedly unsettled by surface dwellers who have breached the Underground ' s most vital sanctum . The Underground dwellers depend on the soil of the planet filtering the surface air and rendering it fit for them to breathe , and without this process the air proves toxic to them ; the Underdwellers have therefore set off the earthquakes in an attempt to seal the opening . C - 3PO offers to fix the damage , and before she dissolves into a swarm of flying fairy sparks , Orphne mysteriously asks the droids to find their true purpose and gives them a parting riddle : " You can run but can not walk " " You have a mouth but cannot talk " " You have a head but never weep " " You have a bed but never sleep " " Ask yourself , who are you ? " With no other option left , C - 3PO attempts to solve the riddle . By viewing the seals in Orphine ' s chamber ( which are in fact elemental signs ) , however , R2 finds the answer first : a river . By wetting the water seal , R2 activates a waterspout which carries the chamber ' s central floor plate — with him and C - 3PO aboard — through the ceiling back to the surface , right into the middle of Manchucho ' s chanting congregation . Poisonous air from the Underground then leaks to the surface through the seal tunnel , and C - 3PO finally understands that , because they are droids and thus not dependent on air , he and R2 are the only ones who can close the breach , which is in fact the unsettled seal . Together , the droids put the seal back into place , ending the earthquakes . Though their efforts go unappreciated with the skeptical clone trooper s , the Aleena give them their heartfelt gratitude and a very cordial farewell . Development . While airing the episode , Cartoon Network erroneously called it " Mercy Mansion . " Continuity . In this episode ' s online episode guide , the title has the tagline , " The Droids Are In Trouble Again ! " " In Trouble Again " was the theme song to the " " animated television series . Reception . " Mercy Mission " was the least watched episode of the series to date with only 1 . 35 million views .