Spock ' s Brain ( episode ) An alien raids the " Enterprise " and steals Spock ' s brain , leading Kirk and McCoy into a desperate race to retrieve it . " ( Season Premiere ) " Summary . Teaser . The crew of the encounters an ion drive vessel , something Scotty finds particularly interesting . Soon though , a strange woman from that ship transports herself onto the bridge and renders everyone on the " Enterprise " unconscious . She slips deliberately among the crew until she finds Spock . Mysteriously , she presses her hand against the first officer ' s head . Act One . When the crew awakens , they find that Spock is missing from the bridge . Dr . McCoy urgently calls Captain Kirk down to sickbay , where he finds Spock on a biobed . McCoy struggles to explain that , somehow , Spock ' s brain has been surgically removed , leaving the body alive but on full life support . Kirk proposes to find Spock ' s brain , but McCoy warns that the unique properties of Vulcan physiology give them only 24 hours to reintegrate it into the science officer ' s body . The " Enterprise " uses the bulk of those hours following an ion trail to the Sigma Draconis system . Ensign Chekov places a schematic of the system on the viewscreen , pointing out that there are three class M planets . With only eight hours remaining to save Spock , Kirk has time to visit only one of the planets before Spock ' s body expires , so he holds an informal staff meeting on the bridge with Chekov , Sulu , and Uhura to arrive at a decision . None of them seems capable of supporting interstellar flight , but Uhura finds large , regular energy pulsations on the otherwise glaciated and pre - industrial Sigma Draconis VI . The unlikely world thus becomes Kirk ' s best hunch . If he is wrong , Spock will die . Act Two . Kirk , Scotty , Chekov , and two security officer s beam down to the frigid surface . There , they detect five large , primitive male humanoid s . Following an ambush , Kirk subdues one of the humanoids with his phaser . The humanoid , a Morg , is confused because Kirk and Scott do not seem like " the Others " , whom he describes as being the givers " pain and delight . " Kirk is puzzled because the Morg does not understand what it means to have a mate nor does he seem to understand exactly what a female is . Chekov finds evidence of an underground city with his tricorder . Scott finds food and weapons stored in a cave , but Kirk discovers a sensor and surmises that the cave is a trap the Eymorg use to capture the male natives . McCoy beams down with Spock , whom he has fitted with a remote - controlled device to substitute for his brain . They allow themselves to be captured . Chekov and the " Enterprise " security officers remain above ground ; Chekov uses his phaser to heat a rock to help them stay warm , since Kirk and company may be a while . In the underground city , they encounter Luma , one of " the Others " – a race of beautiful females , the Eymorg , who live in comfort below the surface of the planet , but have the minds of children . Captain Kirk finds that he is able to establish contact with Spock ' s brain by using his communicator . Spock reports that he is well but that he does not know where he is . They find the woman they saw on board the " Enterprise " immediately before Spock ' s brain was removed , who renders them unconscious by pressing a button on a device located on her wrist . They are taken prisoner . Act Three . When the landing party comes to , they find that they have been outfitted with silver belts that have large , round green devices at the abdomen . Kirk demands to know what has happened to Spock ' s brain , but the Eymorg do not understand what a brain is or what is the " Enterprise " . Finally they understand that the " Controller " the Eymorg speak of is Spock . It seems that these women have somehow connected Spock ' s brain into their computer and that his brain is responsible for running their expansive underground dwelling because they , as a race , have long forgotten how to take care of themselves . Having been left alone , McCoy , Scott , and Kirk incapacitate the guards . Kirk speaks to Spock using the communicator . They inform him that his brain has been removed and it is being used as some sort of controller . Spock reports that he has a body that stretches into infinity and his medulla oblongata seems to be breathing , pumping blood , and maintaining temperature . Spock suggests that the project to restore his brain might be impractical ; he would trust McCoy to remove a splinter or lance a boil , but the knowledge to replace his brain does not exist in the universe . Kirk , however , insists that if the knowledge exists to remove his brain , there must be knowledge to put it back . He instructs Spock to send out a signal so that they may find where he is being kept . Spock complies . As they make their way to the chamber , Kirk asks about the belts . Spock accesses the information : one must press a red button on a bracelet in order to release the belt . They enter the chamber where Spock ' s brain is kept , but an Eymorg is in the chamber and activates the pain belt . Kirk uses the remote control device to use Spock ' s body to grab ' s bracelet and press the red button , releasing the belts . With the crew freed , Kara pleads that Spock ' s brain must remain connected or their civilization will die . Kirk tells Spock that he is in a black box connected by light rays to a control panel . He wonders if the sensations he is feeling means that Spock is recirculating air , running heating plants , and purifying water . Kirk asks Kara how she was able to remove Spock ' s brain by placing on her head a device known as the " teacher " . They place it over her head , and she suddenly speaks with erudition . She admits that she does have the knowledge , but she also now knows to use a phaser , which she points at Kirk . It is set to kill . Act Four . Kara and Kirk debate over the proper disposition of Spock ' s brain . Scott pretends to faint and distracts Kara ; they obtain the phaser from her . She says that the teacher will provide knowledge for three hours , which McCoy says would be just long enough to effect the transplant , but she refuses to perform the operation . McCoy points out that he has medical knowledge and should be able to use what he already knows and retain the knowledge . McCoy places the teacher on his head and receives the knowledge ; when he recovers , he says " " Of course ; of course . A child could do it . A child could do it . " " McCoy begins quickly restoring Spock ' s brain , using the same knowledge originally used to remove it . However , after a time , McCoy begins losing the knowledge he has gained . He exclaims in despair , " " I am trying to thread a needle with a sledgehammer ! " " Drawing on his own skills with only a few minutes left , he connects Spock ' s speech center , allowing Spock to speak . Spock then assists McCoy in completing the reconnection of his brain . " " I ' ll never live this down , " " McCoy says , " " this Vulcan is telling " me " how to operate . " " Upon his restoration , Spock makes a speech that explains the history of this retrograde civilization and the split of the sexes . McCoy then laments , " " I should have never reconnected his mouth . " " " " Well , we took the risk , doctor , " " Kirk jokes . Memorable quotes . " " His brain is gone ! " " " " What if you guess wrong , captain ? " " " " If I guess wrong , Mr . Spock is dead . Spock " will " die . " " " " Call Chekov and tell him to send my stomach down . " " " " Brain and brain ! What is brain ? ! " " " " Pain and delight , he said up above . " " " " I ' m sure you noticed the delight aspect . " " " " Yes , I certainly did notice those delightful aspects . " " " " This fellow is keeping us from our property . " " " " Well , isn ' t there a way to correct that situation ? " " " " While I might trust the doctor to remove a splinter or lance a boil , I do not believe he has the knowledge to restore a brain . " " " " The Controller is young and powerful . Perfect ! " " " " How very flattering . " " " " No one may kill a man . Not for any purpose . It cannot be condoned . " " " " A child could do it . " " " " I should have never reconnected his mouth . " " " " Well , we took the risk , doctor . " " Background information . Remastered information . The remastered version of " Spock ' s Brain " aired in many North American markets during the weekend of . The episode marked several script - appropriate departures from the original broadcast version . Given the generic design of the original ion starship , it would seem unlikely that Scotty could have recognized its propulsion system just by the hull design . The remastered version thus gives the hull a unique , easily identifiable shape . The CBS description of the model stated : The planet Sigma Draconis VI received a fresh , computer - generated appearance both from orbit and from the surface . In the original orbit shot , the planet appears to have a wide band of ocean peeking out from a less - than - uniform ice cap . In the remastered version , the ice coverage is solid , with only small strips of land present , as the script demands , " at the tropics " . Also , the color of the planet from orbit closely matches the color of the land on the surface . On the surface , the landscape has been modified as well . In the original , there was only a slight indication that the action was taking place on a planet that was mostly ice . By contrast , the remastered version makes this more apparent through the use of a new matte painting . Links and references . References . 1485 ; 2030 ; apish ; atrophy ; autonomic nervous system ; boil ; blood ; " Bones " ; brain ; bread ; class M ; control bracelet ; Controller , the ; deaction shift ; Earth ; evolution ; Eymorg ; Eymorg starship ; forge ; foundation ; ganglia ; heating plant ; ice ; industrial development ; industrial scale ; infinity ; ion power ; ion propulsion ; ion trail ; glacial age ; Great Teacher ; lancing ; life support ; magnetic lock ; manager ; medulla oblongata ; meter ; mile ; Milky Way Galaxy ; ; Morg ; needle ; nerve ; neural stimulator ; nitrogen ; nuclear pile ; organizer ; oxygen ; pain band ; physiology ; priestess leader ; red alert ; remote control ; Roman s ; sapient life ; Sigma Draconis primary ; Sigma Draconis system ; Sigma Draconis I ; Sigma Draconis II ; Sigma Draconis III ; Sigma Draconis III native s ; Sigma Draconis IV ; Sigma Draconis IV native s ; Sigma Draconis V ; Sigma Draconis VI ; Sigma Draconis VI native s ; Sigma Draconis VII ; Sigma Draconis VIII ; Sigma Draconis IX ; sledgehammer ; sonic separator ; spaceship ; spectral type ; speech center ; splinter ; standard interstellar symbols ; ; surgery ; tape ; technological rating ; tempering ; training device ; transferal beam ; tri - laser connector ; vocal cords ; volcano ; Vulcan ; water purifier