Kill the Moon ( TV story ) Kill the Moon was the seventh episode in series 8 of " Doctor Who " . Narratively , it saw the Twelfth Doctor take Coal Hill School student Courtney Woods on a trip to the Moon following her discovery of his true nature in the previous episode . It also revealed the true nature of the Earth ' s natural satellite , which had been a fixture of many previous stories . It revisited the Earth ' s environmentally disastrous mid - 21st century as well as the concept of time in flux , with the Doctor choosing to take a step back and leaving the future in the hands of his human company , a choice that would lead to a divide between the Doctor and Clara . " Kill the Moon " was also notable from a production standpoint . Lanzarote was utilised as a filming location for the first time since 1984 when it stood in for " Planet of Fire " s Sarn . The production team played upon this — early drafts of the script were titled " Return to Sarn " just to mislead those who theorised that this story would feature the return of the Master . The concept behind the episode came to writer Peter Harness in 2011 , so initially it was written for Matt Smith . Harness expressed a belief that the script suited Peter Capaldi more with the Doctor - Clara dynamic playing out better . ( DWM 478 ) . Synopsis . The Doctor , Clara , and Courtney go visit the Moon in 2049 , where they discover that the Earth ' s constant companion is a little more than another mere celestial body . Plot . In Coal Hill School , Clara tells the Doctor that her troublesome student Courtney Woods has become worse thanks to meeting him . She ' s even stolen his psychic paper ; the Doctor wonders if it ' s to get into museums . However , Clara tells him Courtney has been using it to get into clubs . And all of this started when the Doctor told her that she wasn ' t special ; it ' s very damaging to a teenager ' s psyche . Entering the TARDIS , Courtney ' s already there , and has bought travel sickness bracelets in preparation for her travels , which Clara tells her won ' t happen . The Doctor on the other hand , is pleased by this news ; he has two rules : no vomiting or hanky panky in the TARDIS . Pestering the Doctor to try making amends with Courtney , he offers to let her big the first woman on the Moon . When asked if it would make feel special enough , Courtney excitedly tells him yes . The TARDIS arrives in the cargo bay on a space shuttle , with the trio exiting in spacesuits . Courtney is not pleased ; however , the Doctor notes from the window that they are on their way to the Moon , so he didn ' t go too far off course . He examines the cargo , explaining the objects around them are nuclear bombs , about to arrive on the lunar surface in 2049 . The astronauts , Lundvik , Duke and Henry discover them , as the Doctor awkwardly walks around ; he asks if they are going to shoot them , telling them to start with Courtney , to make sure she isn ' t last and afraid . He then adds that he ' ll take some time to kill , as he might keep regenerating forever . Introducing himself as an intelligent and benevolent alien , the Doctor asks if the astronauts will still shoot them ; Lundvik says no . The Doctor is glad to hear it , before asking what is wrong the yo - yo he is playing with ; Clara tells him it goes up and down , prompting him to congratulate her . The gravity on the moon has likely increased ; they should all be floating around the room . Lundvik explains the Moon has put on weight , and it ' s causing havoc on Earth . The Doctor laughs " And so they sent you up here to save the Earth with your bombs . " The shuttle lands , and everyone dons their helmets . Courtney exits first , reciting rather poorly Neil Armstrong ' s speech . Lundvik explains that Mexicans were previously sent to investigate the possibility of minerals on the Moon , but all that was sent back were screams over the radio . The Doctor wonders if they are a rescue team , prompting Lundvik to reveal that this happened years ago ; humanity lost its interest in going into space . Even the shuttle had to be put back together from being a museum ride ; her two companions are " third rate " astronauts . They find the mining base , and enter ; the Doctor tells them that oxygen is still in their , so they can take off their helmets to conserve their suits ' s supply . However , they soon discover the corpses of the crew preserved in webs and research photos showing deformed landmasses ; the Moon is disintegrating . Henry investigates a cave outside the base , and is killed by a large spider , one of which then enters the base and begins menacing the Doctor , Clara , Courtney and Lundvik , and kills Duke . Courtney kills it with a detergent , and the Doctor works - out that they ' re germs . Courtney asks to return home out of fear . Courtney ' s taken back to the TARDIS , and Clara tells the Doctor she knows the Moon isn ' t destroyed , having seen it above Earth in the future , but the Doctor ' s open to the possibility of it being a hologram or something similar . The events happening on the moonbase are a fluxed point in time — he doesn ' t know what happens , so the moon could be destroyed , affecting humanity ' s future . Going to analyse one of the crevices caused by the corrosion , the Doctor , Clara and Lundvik find Henry ' s corpse , where he ' s attacked by another spider , which is repelled by the deterring effects of sunlight . The Doctor jumps down the crevice to gather a sample . The Moon shakes , and sheds more of itself . Based on the seismic activity and the amniotic fluid the Doctor finds , he determines that what everyone calls " the Moon " is the egg of the real Moon : the creature within . In 2049 , it ' s hatching , after growing for millions of years . Lundvik wants to know how to kill the moon . The Doctor puts her plan in context — to blow up a new creature with nuclear bombs , something they ' ll have to explain to their descendants . Lundvik reasons that the Moon ' s disintegration is causing catastrophic weather effects on Earth , and needs to be destroyed to save the world . Not being from Earth or the Moon , the Doctor chooses not to interfere , insisting that only Humans can decide the future of their planet . Courtney wants to return to be a part of the debate , and the Doctor instructs her over her phone how to bring the TARDIS to him . As soon as she does so , the Doctor departs — leaving only Clara , Courtney and Lundvik to make the choice . Clara thinks they should take the risk , and deal with any possible consequences if / when they happen . Lundvik has only humanity ' s interests to mind , and is prepared to kill the creature to stop the destruction . She activates a timer , after which , she ' ll detonate the bombs . Ground Control speaks to them over a screen , informing them that Earth ' s situation is " pretty bad " . Clara broadcasts to Earth over the screen , telling them to give their vote . Turning their lights off votes " kill " and keeping their lights on votes " don ' t kill " . After the timer has elapsed , Earth has voted " kill " . Lundvik primes the detonator , but Clara intercepts at the last second and overrides the command , just as the Doctor returns . Returning to Earth , the Doctor , Clara , Courtney and Lundvik watch from a beach as the Moon disintegrates in space , while the creature it hatched ( a massive butterfly - like creature ) flies away — but not before it lays an egg , which has become a replacement Moon . The Doctor tells Lundvik that humanity from this point spreads into space , enduring to the end of the Universe , because they chose not to kill . Courtney realises how special she now is , being one of the three people to allow Humankind to continue . Clara storms out of the TARDIS , which dematerialises . Danny finds her in her classroom , and as he comforts her , she recounts the story to him . Danny tells Clara her relationship with the Doctor isn ' t over , because he can still make her angry . Clara asks him how he became so wise , and he tells her that he left the army under circumstances that he only refers to as a " really bad day " . Returning home , Clara goes into the kitchen and pours herself a glass of red wine . She then gazes out of her window at the Moon . Story notes . Production errors . " to be added " External links . " to be added "