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. Like Series 3's Utopia - Last of the Time Lords, this episode makes it and the previous two a three-parter. 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. 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, the filming for this episode started a long-standing relationship between David Tennant and Moffett; they would later marry on 30 December 2011. In retrospect, not only is Moffett the Doctor's daughter twice, but she is also in a way the Doctor's wife.

Synopsis
Just after stopping the Sontarans from converting Earth into a new clone hatchery, the Doctor, Donna Noble and Martha Jones are taken by the TARDIS on an unexpected trip through time. Arriving right in the middle of a war on the planet Messaline, the Doctor meets someone he thought he never would: his daughter. Can the Doctor accept that he has a daughter and can he stop the war before both sides massacre each other?

Plot
The Doctor's TARDIS continues to fly out of control as the Doctor's attempts to gain control of his vehicle fail repeatedly. Martha and Donna are having trouble keeping their balance. 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; the Doctor raises his hands and shows them 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 Progenation machine near by. The Doctor jokes, knowing it isn't "going to take my blood pressure" as Martha and Donna ask what they are doing to him. Cline explains everyone gets processed. In between yelps of pain, the Doctor figures out that the machine is taking a sample of his tissue and is using it in the "cabinet" device attached to it.

The machine releases his hand and Donna and Martha look down at his hand to see a y-shape of skin missing from his hand. 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 the lead soldier. As the girl preps her weapon, both Martha and Donna wonder who she is and the Doctor explains 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 she can be his daughter. The Doctor explains the progenation 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.

Just then, someone breaks in and Cline yells that it's the Hath. Each of the armed sides fire at the other as the Doctor, Donna and Martha hide. However, just as the two soldiers accompanying Cline are shot, Martha, mistaken for one of the soldiers, is taken by one of the 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. Angry, the Doctor demands to know why, to which his daughter explains is because they shot at them. The Doctor tells her Martha was kidnapped, but his daughter says her capture is collateral damage, believing him lucky; he still has Donna, but Cline lost his men. Angered, Donna tells "G.I. Jane" Martha is not; they decide to go look for Martha. However, Cline points his gun at them, confused, saying they don't make sense as they don't have marks or a will to fight; they'll be taken to General Cobb for interrogation.

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 has been injured by the explosion. 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 different than 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 Doctor Martha Jones, who the hell are you?"

Elsewhere, the Doctor and Donna are being escorted to Cline's camp and ask where they are. The answer is that they are on Messaline or what's left of it. Donna then wonders what name the Doctor's daughter has, 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 wonders about "generated anomaly" and decides to name her Jenny based on it, which Jenny accepts. Donna asks the Doctor about Jenny's name, only for him to give an indifferent answer. Donna believes he's not much of a natural parent, whichs makes the Doctor remind her that a sample of his DNA was stolen at gunpoint and processed; she simply mentions another way children can be conceived. He asks her if he can extrapolate a relationship based on an accident, to which Donna points out, "Child Support Agency can". The Doctor 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 Ms Saigon". Cline walks over with an elderly man, who the Doctor addresses, "General Cobb, I presume?" Cobb explains he has been told the Doctor and Donna were found in the eastern tunnels and with no marks, going on to explain there were pacifists 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.

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 since the outside is too dangerous. Continuing, 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 is lost somewhere 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. Although the exact nature of what they are saying is not known to the viewer, Martha appears to at least partially understand them thanks to the TARDIS Translation circuits; she never went somewhere in time with the Doctor where English was not spoken. Back at the human camp, the Doctor wonders if the map covers the Hath part of the city as well, which Cline answers yes; the Doctor 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 progenation machines to create a platoon. Donna is mortified at the idea of using a machine to make sons and daughters, apologising to Jenny as she does not see her as a real person. Jenny defends herself by saying she has independent thought and a will of her own, 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 in his army. Yelling in success, the Doctor explains there is a suppressed layer of information and uses his sonic screwdriver on the map 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 between the humans and Hath.

Cobb begins ordering his soldiers to prepare for a final battle for "peace in their time". However, the Doctor points out he is contradicting himself as peace and genocide are two different things. Cobb believes that they mean the same thing in this war, but 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 simply 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 because of such.

Once inside the cell, Donna notices that there is another plaque with numbers and wonders what they mean. The Doctor tells her they make as much sense as the Breath of Life story Cobb told them, prompting Donna to wonder if it's really true. However, the Doctor points out that "the Source" may exist, but might not be a mythological breath from a goddess; it may be a weapon. Donna becomes as equally worried and is annoyed 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, the Doctor 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 as it is 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 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 this and encourages Jenny to keep going. The Doctor calls Martha and is relieved she is alright and tells her that 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 a three dimensional projection, 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, inviting Peck to come along with her.

Elsewhere, to force the Doctor to realise that Jenny is actually his daughter, Donna uses his stethoscope to show him that she has two hearts, proving she is the same species. The Doctor, however, insists that Time Lords are defined by their shared tragedy and therefore Jenny is not a Time Lord. Jenny is confused by this as she had only the knowledge of this planet in her head and in the explanations the Doctor admits that he killed during the Last Great Time War, which he greatly laments doing. 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 short cut. 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, but begins to inescapably sink himself. Martha is devastated and weeps bitterly as the wind howls and her friend disappears beneath the surface.

Elsewhere, the Doctor, Jenny and Donna have found the secret entrance. Donna finds another plaque and asks for a pen and paper from the Doctor's coat, saying the numbers on the plaques are going down the closer they get. Jenny notes they are always thinking and asks who the Doctor is, only to get "the Doctor" as an answer. Jenny wonders if he's an anomaly of a machine, too, but the Doctor tells her he is not while Donna says "You're the most anomalous bloke I know". Jenny asks what they do. Donna says they save planets, rescue civilisations, defeat terrible creatures and do an awful lot of running. This leads to a conversation about Jenny's future and to her happiness, the Doctor wants her to come with him. 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 chooses to shoot a pipe 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 her father 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, Jenny and Martha are reunited in the temple, which the Doctor realises is the original and fully functional colony spaceship. This puzzles him as the ship is obviously well-maintained. They find a computer that says the mission commander of the colonisation for Messaline died of Byzantine fever and the human and Hath dived into factions over a power vacuum. Donna stares at a digital clock on the wall. Suddenly, she realises something obvious. The numbers are dates; the city was built in sections outward from the spaceship. The clock shows that it has been a mere week since the ship landed. The Doctor realises that the term "generations" is relative. The technological reproduction system of the humans and Hath allows for as many as twenty generations in a single day; they have turned their history into a mythology. They suddenly smell flowers and race to the very top to find "Kew Gardens", which houses the fabled Source, a terraforming device to make hostile environments habitable.

Cobb's army and the Hath army arrive and 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 terraforming 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, shoots 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, Jenny will regenerate. However, Martha says that she must not be enough like the Doctor to regenerate, but the Doctor says 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 his head, looking on in anger, shocking his companions. Cobb is equally shocked, but further shocked when the gun is lowered. The Doctor looks him straight in the eyes and says, “I never would”. Yelling, 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, They had just gotten there a little too soon; thus they ended up creating Jenny in the first place. "Paradox, an endless paradox". 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 cloud of green gas from the Source 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. 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 is has a lot to see, planets to save, rescue civilisations, monsters to defeat, and an awful lot of running to do.

Cast

 * The Doctor - David Tennant
 * Donna Noble - Catherine Tate
 * Martha Jones - Freema Agyeman
 * Jenny - Georgia Moffett
 * General Cobb - Nigel Terry
 * Cline - Joe Dempsie
 * Hath Peck - Paul Kasey
 * Hath Gable - Ruari Mears
 * Carter - Akin Gazi
 * Soldier - Olalekan Lawal Jr
 * Avolaski - Jeremia K. Fredrick

Production crew
to be added

Story notes

 * Russell T Davies has stated that this episode "does exactly what it says on the tin". Stephen Greenhorn's episode has the Doctor facing a dilemma unlike any before, and it is wildly different to The Lazarus Experiment. He also said that his episode was designed by Russell to "change the Doctor" in a big episode that will have "a real impact on him" and that, in terms of the series continuity, it will be a "lasting impact".
 * Stephen Greenhorn wrote The Lazarus Experiment which coincidentally was also the sixth episode of the series it was in and also followed a two part story by Helen Raynor that featured a returning enemy.
 * Georgia Moffett is the real-life daughter of Fifth Doctor actor Peter Davison. In 2004 Georgia asked to be considered for the role of Rose Tyler; she also auditioned for a role in The Unicorn and the Wasp. Her appearance comes not long after her father guest-starred in Time Crash. A few months after filming, David Tennant and Georgia Moffett began a romantic relationship. In summer 2010, Moffett became pregnant with the couple's first child, which led to them moving in together and becoming engaged later that year. In March 2011 Moffett gave birth to a daughter named Olive, and she and Tennant married on 30 December 2011. He also adopted her older child.
 * Jenny's impressive acrobatics in a corridor full of deadly laser beams was inspired by Britney Spears' Toxic video. Toxic was played during The End of the World.
 * The two Hath named in credits would appear to be named after famous actors, "Hath Peck" drawing his name from and "Hath Gable" taking his from actor . Whether this is deliberate or a mere coincidence is uncertain.
 * Donna Noble came up with the name Jenny after the Doctor said she was a "Generated Anomaly".
 * According to the BBC Podcast Russell T Davies said the original intention was to kill Jenny off at the end of the episode. It was Steven Moffat who expressed the desire to bring her back to life.
 * This episode is one of several that were not featured in the official Series 4 trailer.
 * According to the book Doctor Who: Companions and Allies, it was the Source that brought Jenny back to life although this may be incorrect.
 * This is one of the few televised story titles to incorporate the name "The Doctor" (not counting two early occasions where the incorrect name "Doctor Who" was used). The only other times "The Doctor" appeared in an individual episode title was "A Holiday for the Doctor", episode 1 of the 1966 serial, The Gunfighters, The Doctor Dances, Vincent and the Doctor, The Doctor's Wife and The Name of the Doctor.
 * Donna's surprise aptitude with mathematics foreshadows her later transformation to DoctorDonna.
 * The humans' weapons used are modified real-life weapons. The Hath use weapons that may possibly be modified real weapons, but may also be fakes. For example, Jenny enters the episode and is given a modified P90 with a long silencer and a longer butt stock.
 * It is unclear whether Martha gradually begins to understand Peck and the other Hath by interpreting body language and expressions, or if the TARDIS communication circuits are translating for her (but not for the audience).
 * As is routine for post-2005 Doctor Who, a "NEXT TIME" trailer for the next episode is shown at the end of the episode.

Ratings

 * Final BARB ratings - 7.33 million viewers
 * Sunday night BBC3 repeat - 0.95 million viewers

Studio

 * Upper Boat Studios, Trefforest

Location

 * Aberbaiden Open Cast Colliery, Nr Kenfig
 * City Hall, Cardiff
 * Newbridge Memorial Hall, Newbridge
 * Dupont Building, Pontypool
 * Plantaisia, Swansea
 * Rhondda Heritage Park, Nr Pontypridd
 * Johnsey Estates, Pontypool
 * Barry Shooting Range, Barry Island
 * Mark Street, Cardiff
 * Roath Conservatory, Cardiff

Myths and rumours

 * Jenny would be Susan's mother. This proved to be false.
 * Other rumours reported online included the possibility of Jenny being Rose Tyler's offspring (owing to both being blonde and also because of Rose's background appearances thus far in the season), which was disproven in the pre-credits teaser.
 * It was also rumoured that Jenny was a clone, a hologram, an illusion or something of that sort. All of these proved to be false, to one degree or another. Technically Jenny is not a clone; she is actually the Doctor's daughter, via asexual reproduction through a process similar to parthenogenesis.
 * The initial televised trailer showed Jenny kissing an individual on the mouth; due to the fast-cut editing of the trailer, the gender of the individual being kissed was not clear, leading to speculation, ultimately debunked by the episode itself, that Jenny would engage in a same-sex kiss - the character being kissed turned out to be male.
 * As Steven Moffat is credited with "saving the life" of the character by suggesting to Davies that she not be killed off (a claim Moffat has downplayed if not disputed), rumours emerged that the character may return either as a guest, a recurring role, or as a companion in 2010 when Moffat took over. Although Georgia Moffett is on record as being willing to return to the role, as of late 2012 no announcement has been made regarding her character.
 * A rumour related to the above had Jenny returning for the Series 4 finale; except for a brief flashback appearance recalling her "death", she did not.

Production errors

 * At one point in the TARDIS a studio light is visible near the right of the controls.
 * As the Hath carry the battering ram, the leader holds up a hand to stop the others. However, the Hath can be clearly heard to say "Halt!", despite the species communicating only via bubbles and groaning.
 * When Martha enters the space ship after travelling the surface it cuts to the Doctor, Donna, and Jenny but when they cut back to Martha it shows her entering again but from a different angle.
 * The guns that the Hath and humans use actually spit out small flames; it's easily identified.

Continuity

 * This is the third story in which Martha is kidnapped (the first is TV: Gridlock, the second is TV: The Sontaran Stratagem).
 * The First Doctor was travelling with his granddaughter Susan Foreman, who is to date the only relative of the Doctor to be seen on screen. The Doctor's other two grandchildren, John and Gillian, also appeared in some of the comic strips, although their canonicity is questioned.
 * In TV: Fear Her, the Doctor mentions to Rose, "I was a dad once."
 * In TV: The Empty Child, Dr. Constantine says, "Before the war, I was both a father and a grandfather." The Ninth Doctor replies, "I know the feeling."
 * The Doctor mentions his family. His family is first mentioned in TV: The Tomb of the Cybermen and then in TV: Delta and the Bannermen. His granddaughter first appeared on screen in TV: An Unearthly Child, which was the very first episode of the entire Doctor Who series. He has a brother who first appeared in PROSE: Theatre of War (mentioned on screen in TV: Smith and Jones), an (adoptive) daughter called Miranda Dawkins who first appeared in PROSE: Father Time and a wife. (TV: Blink, PROSE: The Infinity Doctors/PROSE: Cold Fusion) He has cousins who appeared in PROSE: Lungbarrow.
 * The Seventh Doctor says that he does not know if he has any living family members in TV: The Curse of Fenric; in TV: The Tomb of the Cybermen the Second Doctor says he believes them to be dead, though he could have been speaking metaphorically.
 * At the end of this episode Jenny escapes from Messaline in a stolen spacecraft to travel the universe. This mirrors her father's actions. Stylistically, the interior walls of the craft Jenny steals is reminiscent of the TARDIS' interior throughout the original series.
 * Martha mentions the events of the sword fight in TV: The Christmas Invasion when discussing the Doctor's hand. Donna indicates that she wasn't aware of the origins of the hand before this point.
 * Donna mentions her friend Nerys who appeared in TV: The Runaway Bride, and describes how she got pregnant using a turkey baster.
 * Again the Doctor and Donna are mistaken for a couple.
 * Just like Rose Tyler, Donna expresses interest in staying with the Doctor "forever".
 * Cobb's claim that he wants to wipe the last stinking Hath off the face of the planet is similar to the Ninth Doctor's statement with regards to the Daleks.
 * This is the second time in the revived series that the Tenth Doctor has cradled a Time Lord while they die. The first was in TV: Last of the Time Lords.
 * The wound on the Doctor's hand from the device that took his tissue resembles the scar left on the Empty Children. (TV: The Empty Child)
 * This is one of the rare times in the series where an alien language is not automatically translated for the audience. (TV: The Christmas Invasion)

Home video releases

 * This story was released in the Series 4 DVD box set in November 2008 along with the rest of the series.
 * It was released as Series 4 Volume 2 in a vanilla edition with The Sontaran Stratagem, The Poison Sky and The Unicorn and the Wasp.