Cold War ( TV story ) This episode once again implies that wars are fluxing points in the timeline ; " Victory of the Daleks " , the Doctor kept World War 2 from major change by confiscating leftover Dalek technology . In this story , the Doctor explains that history is full of times when all - out war can be triggered by a " single spark " . As something of a surprise , this episode is the first time that one of the Doctor ' s companions has actually listened to his order to remain where they are in a dangerous situation . By this point , the Doctor had come to accept no - one listens to him until right before it ' s too late ; Clara actually listening to him was a shock which immediately set her apart from other companions . Synopsis . In 1983 , the tensest point of the Cold War , a Soviet submarine discovers a strange creature frozen in the ice of the Arctic . When one of the " Firebird " s crew breaks it free , it starts attacking . As the crew strikes back , the Eleventh Doctor warns them that the attack could be considered a declaration of war on the entire Ice Warrior race . . . Plot . It is the North Pole , in the year 1983 . Aboard a Soviet submarine , a warning repeats that the " signal is genuine . " Captain Zhukov and Lieutenant Stepashin use their keys to prime an ICBM launch . They prepare to fire , but are interrupted by the entrance of Professor Grisenko , singing Ultravox ' s " Vienna " . The Captain reports the drill has been abandoned . Stepashin says they must run it again , to which the Captain says , " Tomorrow . " The Captain then asks the Professor about the " specimen " , wondering if it ' s a mammoth . In the hold , the crewman in charge of the specimen muses that they are supposed to wait till the crew arrives back in Moscow to thaw the specimen out . However , he uses a blowtorch to thaw the block of ice , until he is grabbed by a claw that emerges from the ice . Havoc erupts on the submarine . The hull has been breached and crew members are being attacked by a green armoured figure . The TARDIS materialises in the midst of the chaos . As the Captain orders the sub to be brought to the surface , the Eleventh Doctor and Clara are thrown across the bridge . Clara concludes that they are not in Las Vegas , as they expected to be . The Captain asks who they are , while being informed by a crew member that the main turbines aren ' t responding . The Doctor tells them their only chance to survive is to use the lateral thrusters in order to land on a ridge , which will prevent them from dropping further . The captain then orders the crew to do this . Crew members search the Doctor and Clara , confiscating a number of items from his pockets , including a doll , a ball of yarn and his sonic screwdriver . Unexpectedly , the TARDIS suddenly dematerialises . Clara falls into a puddle after a jolt rocks the sub , temporarily losing consciousness . When she wakes up , the Doctor and the Captain are arguing ; the Doctor defends his and Clara ' s arrival as a coincidence . Seeing that he must calm Zhukov , the Doctor decides " okay , no psychic paper , no pretending to be an Earth ambassador " and explains the two of them are time travellers , using the fact the TARDIS appeared from nowhere as proof . They are interrupted by a raspy noise coming from behind the Doctor . He initially thinks it ' s gas , but turns around to find the green armoured figure . The professor explains it came out of block of ice he believed held a mammoth . A shocked Doctor tells him it ' s an Ice Warrior . Zhukov calls it a monster , but the Doctor tells him Ice Warriors are soldiers that demand respect . He goes on to explain the ice Warrior is lashing out in confusion after being frozen for , as the professor explains , 5 , 000 years . The Doctor asks the warrior for his name , to which is replies Grand Marshall Skaldak ; the Doctor is shocked to hear the name of this Ice Warrior . Stepashin sneaks up behind Skaldak and knocks him out with a cattle prod . The Doctor berates Stepashin , telling them Skaldak is the greatest warrior ever produced by the Ice Warriors . He warns the crew that their only option now is to " lock him up . " Now in chains , Skaldak asks Onegin if he has been asleep for 5 , 000 years . The crewman confirms that this is what the Professor said . Skaldak signals for his brothers to save him . In Zhukov ' s quarters , the Doctor explains that the Ice Warriors are native Martian reptiles that built suits to survive when Mars became too cold for them . A design flaw is that a sudden increase of heat will knock them out , hence why the cattle prod worked ; the Doctor always wondered why this has never been addressed . Skaldak was one of the Ice Warriors ' finest , being honoured so much that his enemies would carve his name into their own flesh before death . Clara is shocked to hear this . However , Stepashin is not willing to believe in " little green men " , instead stubbornly believes that the Doctor and Clara are western spies and that Skaldak is a Western weapon , a survival suit ; he believes Moscow must be told so that they can retaliate . Zhukov only finds him annoying , ordering Stepashin to resume repair work on the submarine . The Doctor tells the Captain that if they had done nothing , Skaldak would have ignored them . However , one of their men attacked him : " Harm one and you harm us all " is the Martian code ; " Skaldak will rain down Hell just for laying a glove on him . " The Doctor points to the headphones on the Professor ' s Walkman , where he can hear the sound of " Hungry Like the Wolf " being modulated by Skaldak ' s distress call . He says that he is the only one who can talk to Skaldak , but the Captain is unwilling to risk his only source of knowledge . It can ' t be the Captain , as Skaldak will be able to tell he ' s an enemy soldier . The Captain points out the Doctor seems like one as well . As it can ' t be the Captain , any of his men , or the Doctor , Clara declares that she ' s the only choice . The Doctor protests , but prepares Clara for the task . Clara approaches the restrained Skaldak , with the Doctor coaching her through an audio link . She salutes him and recites a ritual greeting , followed by more of the Doctor ' s words , before her light goes out . The Grand Marshall speaks to the Doctor directly , and tells a story of singing the songs of the Red Snow with his daughter ( who is now long dead ) . The Doctor attempts to calm Skaldak by explaining that the Ice Warriors are still alive , but " scattered all across the universe " . However , Skaldak refuses to believe him , stating that no help will come for him . Clara has been inching forward . She realises something is wrong , discovering that the armour they have chained is now empty . Skaldak has left it . Skaldak says that it is time he studied his enemies , and swears to retaliate . The Doctor tells Clara to get out of there and begins to rush to her , but the Captain pulls a handgun on him , thinking the Doctor was cooperating with Skaldak . The Doctor tells him he ' s never seen one do this before ; he then adds that he ' s never seen one out of his shell before . The Captain accepts this and lets him go . The Professor says it should be more vulnerable without armour , but the Doctor says it will be more dangerous - to an Ice Warrior , leaving its armour is one of the most dishonourable things it can do . He runs for Clara , who hears hissing and sees Skaldak rush by as she tries to open the hatch . The others reach her and the Doctor pulls her through . She asks him how she did . The Doctor says it wasn ' t a test , but she did great . Grisenko reports that the signal has stopped . The Doctor says Skaldak has given up hope of rescue and now has nothing left to lose . Due to the Ice Warriors living beyond the solar system , the signal is taking longer to reach them ; however , Skaldak does not know this , instead believing he is the last of his kind . The Captain is sceptical about what the Martian could do , until the Doctor points out that they ' re sitting on a large number of nuclear weapons . He says it couldn ' t be any worse , just before the submarine slips a little further down the incline and more water pours in . Skaldak stalks Stepashin , who is making repairs . Stepashin pulls his gun , but he is facing the wrong direction . He feels spindly , three fingered hands grab him by the shoulder and top of the head . Skaldak learns about the Cold War and the theory of mutually assured destruction from Stepashin , who wants to gain an ally to fight Western aggression . The Captain addresses the crew . The reactor is drowned , they only have battery power , and they ' re running out of air . They still have a mission , however . They need to stop the Grand Marshall before he gains control of any of the missile s . They are all that stands between him and the destruction of the world . Clara learns from the Doctor that time can be changed , and even if the world previously didn ' t end in 1983 , it can now . The Captain tells him that they have twelve men , but they can ' t find Stepashin . They decide to split up and look for him , with a team to guard the bridge ; when the Captain questions the idea , the Doctor retorts " it ' s either that , or wait here for him to kill us all . " Grisenko turns up with the sonic screwdriver and the doll and gives them back to the Doctor , who is quite happy to have them both . They begin the search . As the Doctor scans , Clara asks Grisenko why they have a cattle prod on board , and is told that it ' s for polar bear s . The Professor tells her to have courage , and says he sings a song to stay brave . He asks if she knows " Hungry Like the Wolf " . She refuses to sing , comparing it to a musical number in " Pinocchio " . There are alarms and some echoes as the Doctor tinkers . He says it ' s the pressure , and Grisenko begins to sing , trying to persuade Clara to join him . Onegin asks Belevich if he thinks it ' s truly a Martian . Onegin thinks they ' ll be heroes for discovering that there is other life out there in the universe , not just humanity . As Belevich replies , Skaldak silently grabs Onegin . Screams echo , and the Doctor , Clara , and Grisenko arrive to find the two torn apart . The Professor calls Skaldak a savage , but the Doctor explains that he is studying the humans for physical weaknesses . They continue the search , but Clara is slow to follow . Scanning for Skaldak ' s location , the Doctor gets a fix and tells Clara to stay with the professor . Clara agrees to do so . The Doctor is momentarily confused by her willingness to follow his instruction ( unlike most of his companions ) , then continues onward . Clara confesses to Grisenko that she was bothered by the bodies . The Captain realises that Skaldak is in the walls , thus avoiding attention . The Doctor finds Stepashin ' s body , feeling sorrow for him when he notices a photo of a woman in Stepashin ' s wallet . He then spots Skaldak moving above him . He follows . The Professor tries to distract Clara from worrying about the noises she is hearing . He keeps questioning her , but she continues staring around , barely answering . He very seriously demands to know about the future — specifically , if Ultravox will split up . She breaks out into laughter , then gasps as Skaldak grabs her head . Grisenko produces a gun and shoots several times . Skaldak lets her go and grabs him . Clara pleads with Skaldak to let Grisenko go as the Doctor runs up . The Grand Marshall declares that they attacked him . By Martian law , this means that the people of this world are forfeit ; he now has the information he requires to begin the destruction . He only needs one missile to trigger the exchange . With his people dead and dust , there is nothing left for him but revenge . Skaldak signals his armour , and the helmet flips up . The Doctor tells him that there is one thing left : mercy . The Captain enters with a crewman , threatening violence in defence of the Earth . The Doctor says they ' re negotiating , not fighting . The Captain replies that they will negotiate from a position of strength , and aims his rifle . Skaldak comments , " Excellent tactical thinking , " but goes on to explain his position isn ' t as strong as he thinks . The armour has been summoned by Martian sonic technology . He releases the Professor and enters his armour . They open fire , but the Doctor stops them . Skaldak vows to create a new red planet from the blood of humanity . The Doctor follows him . Skaldak extrudes probes from the gloves of his armour into the targeting computers . Text flows , lights change and locks shift . The missile tubes open . The others arrive and the Captain says that the warheads are being armed . The Doctor asks him to wait , asking where the honour is in killing billions of innocent people . He continues to appeal to Skaldak ' s better nature , but seemingly to no effect . As Skaldak reaches for the button , he declares himself as a Time Lord , with his own sonic technology . If he needs to , he will blow up the sub and everyone on it to avoid starting the nuclear exchange . The Martian mutters , " mutually assured destruction , " and turns back to the button , as the Doctor lifts the sonic screwdriver . The Doctor taunts him to look into his eyes , and Skaldak removes his helmet , asking which of them will blink first . Clara asks Skaldak why he showed compassion earlier , further asking about his daughter and when they had sung the songs of the Red Snow . The submarine suddenly begins to vibrate . Skaldak declares that his people live and have come for him . The Captain says that they are rising . A spaceship raises the submarine to the surface in a beam of cloudy white light . The Doctor pleads with Skaldak to just go in peace . Another beam hits Skaldak and he disappears . Clara says they did it , but the Doctor checks the console , which is still armed . One pulse from the Martian ship could launch the missiles . He holds up the sonic screwdriver , wincing and repeating that he ' ll destroy them if he must . Frightened , Clara begins to quietly sing " Hungry Like the Wolf " . The missiles disarm . Clara hugs the Doctor , before straightening herself . " Saved the world , then , " she says . " That ' s what we do . . . " The Doctor , the Captain , the Professor , and Clara go up top and get a look at the Martian ship . Clara asks the Doctor what happened to the TARDIS . The Doctor sheepishly confesses that , while tinkering , he reset the HADS , which he hasn ' t used in a very long time . He says it ' s bound to turn up , as the sonic starts buzzing . The TARDIS has gone to the pole . . . the South Pole . Embarrassed , he asks the Captain for a lift , and they all laugh . The Doctor salutes the Ice Warrior ship with an arm across his chest as it zooms off . Story notes . Ratings . " Cold War " was first broadcast in the United Kingdom on BBC One on 13 April 2013 . Overnight ratings showed that 5 . 73 million viewers watched the episode live , a 28 . 8 % audience share . When timeshifted viewers were taken into account , the figure rose to 7 . 37 million viewers , the fifth most - watched programme of the week on BBC One . In addition , " Cold War " received 1 . 65 million requests on the online BBC iPlayer during April , the fourth most - watched programme on the service for the month . The episode also received an Appreciation Index of 84 . Filming locations . " to be added " Home video releases . " Cold War " , along with the rest of the second half of series 7 ( episodes six through to thirteen ) was released on DVD and Blu Ray on the 27 May 2013 .