The Doctor ' s Daughter ( TV story ) The Doctor ' s Daughter was the sixth episode of the fourth series of the BBC Wales version of " Doctor Who " . It was significant for introducing only the second known genetic relative of the Doctor seen in a televised episode . Additionally , that character ' s fate at the conclusion of the episode left — atypically for most guest characters — obvious narrative possibilities for her return to the programme . From a production standpoint , it was notable for its interesting casting of Georgia Moffett , the real - life daughter of Peter Davison . In giving the part of Jenny to Georgia Moffett , the production team had cast the daughter of an " actor " who had played the Doctor to play an " on - screen " daughter of the character . In addition , this episode marks the first meeting between David Tennant and Moffett ; a year later they started dating , and married on 30 December 2011 , nine months after Moffett gave birth to their daughter , Olive . In retrospect , not only is Moffett the Doctor ' s daughter twice , but she is also in a way the Doctor ' s wife , as well as the mother of the Doctor ' s daughter . Synopsis . Just after finally defeating the Sontaran s on modern - day Earth , the Doctor ' s TARDIS takes the Tenth Doctor , Donna Noble and Martha Jones on an unexpected trip to the planet Messaline . Arriving right in the middle of a war between human s and Hath , the Doctor meets someone he thought he never would : his daughter . Can the Doctor accept this clone as his offspring , and can he stop the war before it all ends in massacre on both sides ? Plot . The TARDIS continues to fly out of control as the Doctor ' s attempts to gain control of his vehicle continue failing . Martha and Donna are having trouble keeping their balance , since the TARDIS ' s flight is more erratic than usual . The console smokes and sparks and the ship bucks violently , hurling its occupants about . The Doctor ' s severed hand bubbles furiously . Seeing this , the Doctor comments his old hand is " liking " their unexpected trip . Donna is horrified by this ; she thought it was just a " freaky alien thing " and not the Doctor ' s hand . Martha explains that the Doctor ' s hand got cut off and he grew a new one , making Donna call the Doctor impossible . The Doctor , however , says he ' s not impossible , " just a bit unlikely " . The TARDIS finally lands , allowing the occupants to catch their breath . The Doctor , Donna and Martha depart from the TARDIS to find themselves in what seems to be an underground bunker . The Doctor is the most confused of the three as he has absolutely no idea why the TARDIS would bring them to a place like this . Martha says she loves stepping out of the TARDIS and into a new world , confusing Donna as she had been yelling at the Doctor to take her home . Having a laugh , Martha and Donna talk about the feeling of seeing new worlds , saying it ' s like having a hamster stuck in your throat . Suddenly , armed men arrive and order them to drop their weapons ; they raise their hands to show they are unarmed . However , the lead soldier , Cline , says the Doctor ' s hands are " clean " and has the other two soldiers take him and force his hand into a machine near by ; the Doctor is confused , wondering what ' s wrong with clean hands . The Doctor jokes , knowing it " isn ' t going to take my blood pressure " , as Martha and Donna ask what they are doing to him . Holding them at gunpoint , Cline explains that everyone gets processed . In between yelps of pain , the Doctor figures out the machine is taking a sample of his tissue and is using it in the " cabinet " device attached to it . The machine releases the Doctor ' s hand ; he and a concerned Donna and Martha look down at his hand to see a thin amount of skin a y - shape missing from the back of it . The cabinet opens with a hiss of smoke and out of it comes a young blonde girl in combat attire , who is given a gun by Cline . As the girl preps her weapon , both Martha and Donna wonder who she is ; a bit stunned by what he ' s seeing , the Doctor explains that she ' s his daughter . The girl smiles at him and says , " Hello , dad " . As the soldiers set up explosives on the walls of the tunnel , Cline questions the Doctor ' s daughter on how ready she is for combat . In the meantime , both Martha and Donna wonder how this woman can be the Doctor ' s daughter ; he ' s told both of them how he became the last of the Time Lord s . The Doctor explains that the machine took a sample of his diploid cells , which were split into haploids , then recombined in a new pattern and grown " very quickly , apparently " into the young girl in front of them . It makes one person biological mother and father ; in short this person just created by the machine is a kind of clone of the Doctor . Just then , someone breaks in and Cline yells it ' s the Hath . Each of the armed sides fire at the other as the Doctor , Donna and Martha hide . Just as the two soldiers with Cline are shot , Martha is captured by a Hath . Cline orders the explosives to be set off . Despite the Doctor ' s protests , his daughter obeys and sets off the explosives , sealing the tunnel , separating them from Martha and the TARDIS . The Doctor demands to know why his daughter did that , to which she explains is because the Hath shot at them . She calls Martha ' s capture collateral damage , believing him lucky ; he still has Donna , but Cline lost his men . Angered , Donna tells " G . I . Jane " that Martha isn ' t collateral damage ; they decide to go look for Martha . However , Cline points his gun at them ; he ' s confused as they don ' t have marks or a will to fight . He explains that they ' ll be taken to General Cobb for interrogation ; seeming to not understand the concept of pacifism , Cline appears to think that anyone not trying to kill the Hath is a dangerous element . On the other side of the rubble , Martha regains consciousness to find herself undamaged and next to the TARDIS with her would - be kidnapper , who ' s injured . Martha instructs the Hath to be still while she examines its injury . She finds it has a dislocated shoulder , but is confused if she is completely correct as a Hath is not a human . More Hath soldiers arrive and point their guns at Martha ; she explains her status as a doctor and that she will not leave a patient in an injured state . She relocates the injured Hath ' s shoulder and the other Hath think she lied . However , the recovered Hath shows them she did help , having its comrades lower their weapons . Picking herself up , Martha greets them . " " I ' m Dr . Martha Jones , who the hell are you ? " " Elsewhere , the Doctor and Donna are being escorted to Cline ' s camp and ask where they are ; Cline explains they ' re on Messaline , or what ' s left of it . Donna then asks the Doctor ' s daughter for her name , only to find out she doesn ' t have one . The Doctor calls her a generated anomaly ; she was bred with military knowledge and common sense , but no name . Donna decides to name her Jenny based on it , which she accepts . Donna asks the Doctor about the name , only for him to act indifferent . Donna says he ' s not much of a natural parent , prompting him to remind her that his DNA was stolen at gunpoint and processed . He asks her if he can extrapolate a relationship based on an accident , to which Donna points out , " Child Support Agency can " . He retorts , " Just because I share certain physiological traits with simian primates , that doesn ' t make me a monkey ' s uncle , does it ? " Jenny misunderstands the conversation , defending herself , " I ' m not a monkey . . . Or a child " . They arrive in the camp to find the human group lives in a theatre ; Cline orders them to stay still while he talks to Cobb . Donna is shocked by this , but the Doctor jokes , " Maybe they ' re doing " Miss Saigon " " . Cline walks over with an elderly man , whom the Doctor addresses , " General Cobb , I presume ? " Cobb explains the Doctor and Donna were found in the eastern tunnels and with no marks , going on to explain there were pacifist s three generations back before they lost contact ; he wonders if they are generations from the pacifists . The Doctor decides to pick up on this easily given lie and says that they are from the eastern zone and asks who the Hath are . In the meantime , Martha has been brought back to the Hath camp and is given a warm welcome due to helping one of their comrades . She is a bit uncomfortable with the attention , but is glad they are not trying to kill her . The Hath are likely happy to have a medic on their side . Back in the human camp , Cobb explains long ago the buildings were built into the ground as the environment is too hazardous . Donna finds a fault with the story ; there are windows , leading to confusion as to why there any constructed at all since outside is too dangerous . Cobb explains Hath and humans decided to build a new society together , but the dream died ; the Hath wanted Messaline for themselves , forcing the first colonists to use the machines to produce soldiers and began the war . The Doctor wonders what they are fighting for and Cobb explains a myth about how a Goddess created the universe , looked at her work and sighed . That sigh was caught in some form which is now referred to as " the Source " . They believe the Source to be lost in the maze of tunnels they show the Doctor on a holographic map . Recovering it could allow them to exterminate the Hath and win Messaline for themselves . Meanwhile , the Hath are showing Martha an identical holographic map . Martha appears to partially understand them thanks to the TARDIS translation circuit s ; she had never went anywhere in time with the Doctor where English wasn ' t spoken . She points at a section of the map , believing it to be where they are ; however , all she earns are sighs due to being wrong . Back at the human camp , the Doctor wonders if the map covers the Hath part of the city as well , which Cline answers yes ; he says it will help them find Martha . Cline says they have more important things to do , but when it ' s morning , they can use the machines to create a platoon . Donna is mortified at the idea of using a machine to have offspring , apologising to Jenny as she does not see her as a real person . Jenny defends herself by saying she has free thought and will , making her just as real as Donna and the Doctor , wondering how they differ ( which is how they were born ) . Cobb shows pride in Jenny , wishing he had more soldiers like her . Yelling in success , the Doctor explains there ' s a suppressed layer of information and uses his sonic screwdriver to reveal a previously unknown route to the Temple where the Source is located . At the same time , the Doctor ' s meddling with the human ' s map has accidentally allowed the Hath to see the new route on their map as well . Martha explains what they are seeing in surprise , but the Hath think she has done something to help them and they pat her on the back , congratulating her for her help . Martha looks on as the Hath wave their weapons . Horrified , Martha thinks she has started a war . Cobb orders to prepare for a final battle for " peace in their time " ; however , the Doctor asks why they don ' t simply stop fighting . Cobb explains once the Source is in their possession , they can wipe out the Hath . The Doctor points out that ' s contradictory as genocide is the opposite of peace , but Cobb says its the same result in war . Seeing Cobb ' s insane , the Doctor tells him , " " You need to get yourself a better dictionary . When you do , look up genocide . There ' ll be a little picture of me there and the caption will read , ' Over my dead body ! ' " . " Cobb mocks the Doctor for showing his army the way to the Source and orders Cline to take arms , threatening to kill his woman ( Donna ) if he interferes . Both the Doctor and Donna dismiss the idea they are together before Cobb orders Jenny imprisoned with them as she ' s " from pacifist stock " and can ' t be trusted . Once inside the cell , Donna notices there ' s another plaque with numbers and wonders what they mean . The Doctor tells her they make as much sense as the story Cobb told them , prompting Donna to wonder if it ' s true . If " the Source " exists , it could actually be a weapon , instead of something mythical . Donna is annoyed that they " gave directions to Captain Nutjob " . The Doctor decides they have to come up with a plan to escape and stop the ensuing bloodbath ; Jenny looks at him in confusion . Equally confused , he asks why Jenny is staring at him . Jenny says that despite saying he is not a soldier , the Doctor is making plans like a proper general . The Doctor tells her that he is trying to stop the fighting ( without violence ) . Jenny tells him every soldier is . Annoyed and not knowing what to say , the Doctor puts the idea aside for now and asks Donna for her mobile , saying it ' s time for an upgrade . The Doctor takes out his sonic screwdriver , and Jenny says he has a weapon now . Further annoyed , the Doctor tells her it ' s not a weapon ( as it cannot wound or kill ) while she laughs that she will learn so much from him as he is " such a soldier " . Speechless , the Doctor tells Donna to talk to Jenny , but Donna is enjoying watching this and encourages Jenny to keep going . The Doctor calls Martha and is relieved she is alright and explains he , Donna and Jenny are as well . However , he becomes grim when he learns his meddling with the map gave the Hath the same directions to the Source as Cobb . The Doctor instructs Martha to stay where she is and to be safe as Martha ' s phone battery goes dead . Meanwhile , Martha and the Hath she healed , Peck , are studying the tunnels as she wonders if there is some place where she can recharge her mobile . Peck works the controls and converts the map into 3D , delighting Martha . Noting that the distance above ground is shorter than the distance through the tunnels , she plans to beat both the humans and the Hath to the Source . However , Peck informs her that it ' s a bad idea as the surface has low radiation levels ; Martha decides that small time exposed to it wouldn ' t having any lasting harmful effects . Elsewhere , Donna forces the Doctor to accept Jenny as his offspring by using his stethoscope to show him that she has two hearts , proving she is the same species as him . The Doctor , however , insists that Time Lord s are defined by their shared tragedy and therefore Jenny is not a Time Lady ; Jenny is confused by this as she had only the knowledge of this planet in her head . The Doctor explains that it all vanished in the Last Great Time War , a war MUCH bigger than this one ; he admits to killing in the war , which he greatly regrets . Jenny then asks how they are different . In the meantime , the Hath have found their side of the entrance into the Temple and use a battering ram to create a shortcut . Martha and Peck reach a hatch and escape to the desolate surface while Martha berates Peck for using foul language when she says he couldn ' t resist seeing the surface . Back at the cell , Jenny seduces the guard and then holds him at gunpoint to force him to open the door . Amused , Donna tells the Doctor , " I ' d like to see you do that " . The Doctor only gives an embarrassed look as they escape . They reach the exit of the camp , only to find another guard . Donna offers to distract this one , but the Doctor tells her that she should save her " womanly wiles " for an emergency ; Donna knows he is lying , but agrees . Using a toy mouse , the Doctor distracts the guard , but Jenny knocks him out with a karate chop . Annoyed , the Doctor tells her to " stand still , don ' t hurt anybody " , while he searches the guard for a copy of the new map . On the surface , Martha falls down a scree into quicksand . Peck leaps in to save her , getting her to the edge of the quicksand , where she climbs out . However , Peck is unable to get out himself ; he sinks beneath the surface , content to have saved her . Martha is devastated and weeps bitterly as the wind howls and her friend disappears beneath the surface . Elsewhere , the Doctor , Donna and Jenny have found the secret entrance . Donna finds a plaque , asking for a pen and paper from the Doctor as she notes the plaques are counting down the closer they get . Jenny notes they ' re always thinking ( which is new to her , having been bred to follow orders ) and asks who the Doctor is , only to get " the Doctor " as an answer ; she wonders if he ' s an anomaly , too . The Doctor says he ' s not , while Donna says " " You ' re the most anomalous bloke I know " . " Jenny asks what they do ; Donna says they save planets , rescue civilizations , defeat terrible creatures and do an awful lot of running - " " seriously , there ' s an outrageous amount of running involved " " . Donna asks the Doctor is Jenny will join them , to which the Doctor agrees to . They get the door open just as Cobb ' s army arrives and seal it shut behind them . After Jenny runs ahead to scout , the Doctor explains to Donna his previous parenting , the pain of losing the Time Lords and his family , and the fact that he is reminded of them when he sees Jenny . They come across a security grid and the Doctor shuts it off just as Cobb and his men break through the door . This gives Jenny an epiphany : follow her dad or shoot Cobb . She shoots a pipe to release some steam to buy time , but doesn ' t make it back to the Doctor in time as the security beams come back on . Jenny abandons her gun and flips through the beams , astonishing the Doctor and Donna . The Doctor yells to Cobb that if the Source is a weapon , he ' s going to destroy it , while Cobb threatens the Doctor ' s life , saying one of them will die , but not himself . The Doctor , Donna , and Jenny discover the Temple is the original spaceship . This puzzles him as the ship is obviously well - maintained , despite having supposedly being abandoned for years . They find a computer that says the colonisation mission commander died of Byzantine fever , causing a power vacuum between the humans and Hath . Donna stares at a digital clock on the wall and suddenly realises what the numbers are . . . dates ; the city was built in sections outward from the spaceship and the dates ( which aren ' t counting " down " , but counting " out " ) mark when each section was completed . The clock shows it ' s been a week since the ship landed . The " generations " mentioned by the soldiers aren ' t years ; they refer to the soldier breed from the Progenation machines . They proceed up the stairs , finding Martha , who tells them she took the surface route . At the same time , the Hath and Cobb ' s forces are cutting through the doors to get inside the ship . The quartet suddenly smell flowers and race to the very top to find a garden kept alive by the Source , a terraforming device to make hostile environments habitable . The original colonists likely died a few days into the war , leaving the soldiers with inaccurate information , leaving them to speculate ; this caused them to fight over nothing . The human and Hath armies arrive , confused , wondering if it ' s a trap . The Doctor explains that they no longer really know why they ' re here as their history is getting more distorted the more it ' s passed on , like Chinese whispers . The Doctor , surrounded by both armies , declares the war over and smashes the Source to release its gases and start the terraform ing process . Both armies lay down their weapons in awe of the new planet forming around them . Jenny wonders what is happening and the Doctor tells her the gases will escape to the outside , triggering the terraforming process , and a new world will be born . However , Cobb , full of malice out of being denied his murder of the Hath , takes a shot at the Doctor . Jenny takes the bullet instead . Both the human army and the Hath army look on in sadness as Cline and two soldiers hold Cobb down . Donna asks Martha if Jenny is going to be okay . However , when Martha takes Jenny ' s pulse , she gives a grim look , signifying she won ' t make it . Jenny dies in the Doctor ' s arms , happy that he invited her to travel with him . The Doctor cries , saying that if they just wait , maybe Jenny will regenerate . However , Martha gently says that she must not be enough like the Doctor to regenerate . The Doctor replies that she was too much like himself . After he lays her head gently on the ground , the Doctor grabs Cobb ' s gun and holds it to the General ' s head , shocking Martha and Donna as he despises guns and violence . Cobb is equally shocked , but further shocked when the gun is lowered . The Doctor looks him straight in the eyes and says in a soft , cold tone , “ I never would ” . Yelling in grief , the Doctor asks that both armies let the idea of a man " who never would " be the foundation of the Hath - human society that must now emerge . The Hath and humans ask the Doctor to allow them to give Jenny a proper funeral , to which he sadly agrees . Later , the Doctor concludes that Jenny ' s creation was the reason the TARDIS had brought them to Messaline . The only problem was that they had just gotten there a little too soon ; thus they ended up creating Jenny in the first place - " Paradox , an endless paradox " the Doctor quips . He returns Martha home , where Martha and Donna talk about travelling with the Doctor . Donna tells Martha , " I ' m going to travel with that man forever " , before returning to the TARDIS . Martha hugs the Doctor and bids him good bye , and the Doctor bids good bye to Dr Jones , returning to the TARDIS . Back on Messaline , Hath Gable and Cline look at Jenny ' s body in sadness . Suddenly , she breathes out a glowing cloud of green and gold and revives , just as the Doctor had hoped . She smiles and says , " Hello boys " , before running off into the ship . Gable and Cline follow her to find she is taking one of the escape shuttles to leave the planet . A concerned Cline asks her what she is doing over the intercom and Jenny asks if he is going to tell her dad on her , saying she has a lot to see , planets to save , civilisations to rescue , monsters to defeat , and an awful lot of running to do .