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Cold Blood was the ninth episode of series 5 of Doctor Who.

It was the second part of a two-part story that featured the return of the Silurians and the first death of recurring companion Rory Williams, which soon escalated further to total erasure from existence after a crack consumed his body. Thus only the Doctor remembers him.

Once more, the Doctor is seen trying to bring about a peaceful solution to a conflict between Silurians and humans. In this case, a rogue Silurian is responsible for the breakdown of trust, as is just one human. It's worth noting that unlike the previous branches of the Silurians, which had a more peaceful nature, Alaya and Restac are shown to be racist and genocidal.

Unlike the previous branches of the Silurian species, which never survived their initial encounters with the Doctor, this one found in Cwmtaff survives for another chance at cohabitation with humanity in the future.

Neve McIntosh, who plays Alaya and Restac, would later return to the show the following year in A Good Man Goes to War, playing another Silurian named Madame Vastra. However, unlike the characters in this story, Vastra would serve as one of the Doctor's recurring allies, primarily in the Victorian Era.


Once more the Eleventh Doctor meets members of the Silurian race. However, this time, can he prevent them from being destroyed by humanity out of an act of self-preservation, or can he broker peace between them and bring about a better future for both races of planet Earth?

In the meantime, there are other questions that are left unanswered: Can Ambrose be trusted to keep Alaya alive? What is happening to Tony Mack's wound? Are the Silurians responsible for the empty graves? And what awaits Mo and Amy when a Silurian doctor is eager to see what makes them tick?


A view of the Earth is shown from space as the sun rises from behind it, illuminating the features of the planet.

A Silurian narrates that his people are now awakening and that he remembers the day 1000 years ago when he met the Doctor and the losses that the Time Lord suffered because of the failed attempt to negotiate peace.

Silurian City

The Doctor and Nasreen explore the city.

Back to the present day in 2020, the Eleventh Doctor and Nasreen enter the Silurian city, which is quite elaborate and grand. A curious Nasreen wonders how any of the vegetation and the city itself could be there, being so far beneath the Earth. The Doctor explains that the city and the vegetation are fueled by thermal energy and most of the Silurians are hibernating in suspended animation. To get back who was taken, they need to find the Silurians that were awakened by the threat the drill posed to the city.

Nasreen wonders if waltzing straight into the city is a good idea as the Doctor assures her that the "front door approach" is always the best idea. An alarm goes off, announcing hostile life forms entering the city. Shocked at being called hostile, the Doctor admits that the "front door approach" may not have been the best idea. They turn to leave, but Silurian soldiers arrive and hold them at gunpoint. The Doctor tells them they are not hostile, but the Silurians knock them out with gas.

Amy and Mo are strapped to surgical operating tables in a Silurian surgery. The Silurian surgeon, Malohkeh, is getting ready to vivisect Amy. He removes his mask and tightens Amy's straps. Malohkeh notes that Amy is reacting differently to the cold than Mo; Amy yells she was dressed for Rio. He then takes the scalpel and begins to put it in Amy's chest, but is called away to examine the Doctor and Nasreen. Amy, who has sneaked the remote controlling the surgical tables from the surgeon, releases Mo and herself and they escape into the city. While searching for a means of returning to the surface, they find Elliot, trapped in suspended animation, but alive.

The Doctor and Nasreen are strapped to tables in a separate laboratory and forcibly scanned; while Nasreen is complacent, the Doctor cries out in pain. Malohkeh converses with Commander Restac, wondering if there has been any word from Alaya. When Restac briskly responds in the negative, Malohkeh assures her that it is all right to show some emotion as they are from the same genetic line. Malohkeh begins to decontaminate the Doctor and Nasreen; again, the Doctor cries out, begging Malohkeh to stop. Because the Doctor is not human, the decontamination process affects him differently — not only does it cause him severe pain, but it "remove[s] half of the things keeping [him] alive". Against Restac's wishes, Malohkeh stops the process after seeing an internal scan confirms his non-human status.

Thanking Malohkeh, the Doctor asks if they have any celery. Malohkeh explains the drill threatened the oxygen pockets above the city; the Doctor is pleased to hear about such technology, but then realises that the impending drill wasn't a very nice greeting. The Doctor asks for Restac's identity, learning to his annoyance that there is a military. Restac demands to know where the rest of their "invasion force" is. The Doctor tells Restac that the two of them are not an invasion force, revealing that they've come down to negotiate a trade of prisoners: Alaya for the three humans the Silurians took. Restac, however, is less inclined to negotiate and orders the execution of Nasreen and the Doctor out of spite.

Ambrose Northover

Ambrose cannot make peace with the Silurians.

On the surface, Tony approaches Alaya for help in curing the venomous sting on his shoulder, promising to release her if she can do something for him. Alaya refuses and amuses herself by having Tony describe what the venom's effect feels like. Ambrose eventually learns of Tony's injury and Alaya's refusal to help. She angrily confronts the Silurian, threatening her with a taser. Alaya encourages her to use it, which she does; on the second shot, Alaya collapses as Tony and Rory arrive, and she dies in Rory's arms. They both become angry with Ambrose because she killed their only bargaining chip to get their loved ones back. Ambrose expresses remorse for what she's done.

Restac and Malohkeh lead the two prisoners to the city's execution chamber, flanked by Silurian warriors. The Doctor explains the nature of the Silurians' hibernation to Nasreen: centuries before, their astronomers predicted a planet was on a crash course for Earth, so they hibernated below the surface to avoid the catastrophe. The planet was, in fact, the moon coming into alignment. Malohkeh is impressed with the Doctor's knowledge of their race, prompting the Doctor to reveal that he'd previously met another branch. Restac is happy to hear more of her race has survived; however, the Doctor sadly informs her that humans killed them, reigniting Restac's rage.

Once inside the execution chamber, Mo and Amy appear, brandishing guns they have taken from sleeping Silurian warriors, with the intention of rescuing the Doctor. Restac swiftly disarms Amy, forcing their surrender. The two are added to the procession. When Malohkeh protests, Restac dismisses him. On the surface, Rory and Tony berate Ambrose for what she has done to Alaya. Suddenly, Restac's face appears on the screen of a deactivated computer monitor in the church cellar. She has somehow manipulated the monitor to address the humans and negotiate Alaya's return. Though the Doctor orders Ambrose to let Rory handle the situation, she steps in and declares she has had enough of the Silurians' orders. She refuses to return Alaya unless Restac releases her family. Angered, Restac orders the first execution: Amy. The computer monitor goes dark.


Restac is stopped by Malohkeh and Eldane.

However, before the Silurian warriors can fire, their leader, Eldane, arrives with Malohkeh and countermands the order. Malohken knew Restac was only acting on bigotry and needed their wiser leader to make the decisions. Eldane tells Restac to "go play soldiers" somewhere else, dismissing her. Now free, the Doctor, realising his chances of negotiating have been reignited, resumes communications with his companions on the surface, ordering them to bring Alaya down via the Silurian transport pods in the mine storeroom. Reaching the mine, Ambrose encourages Tony to reactivate the drill on a timer in case things go wrong.

The Doctor appoints Nasreen and Amy as the ambassadors for humanity and allows them to talk to Eldane. Amy wonders if the Earth is shared in the future, prompting Nasreen to ask what she means. The Doctor reveals that he and Amy travel in time, surprising both Nasreen and Eldane. He then explains time is in flux at this moment, which means they can create a future where humanity and the Silurians live in harmony on the surface, rather than have more genocide. Calling the meeting together, the Doctor leaves with Mo to collect Elliot.

Malohken brings Mo and the Doctor to the stasis chamber Elliot is in; he begins shutting it down. The Silurian explains that he didn't mean any harm, he just slowed Elliot's growth so that he can study how he matures. Malohkeh explains that his family has been studying human evolution through the centuries, but he is the only one awake for the last 300 years. The Doctor expresses his fondness towards a fellow scientist. The boy is released and the Doctor apologises for putting him in harm's way. Elliot happily forgives him.


Malohkeh sees Restac's insanity worsen.

The Doctor, Mo and Elliot return to the negotiations, but Malohkeh opts to stay behind to check something. Hearing that cryo-storage has been opened, he rushes to see what is happening. He discovers Restac has awoken more of her warriors. She states that she is protecting them from the apes, clearly showing that she has been consumed by xenophobia towards humanity. Restac tells Malohkeh that he has done good work, but has no place during a war; she kills him, leaving the others unaware of her growing insanity.

Amy, Nasreen and Eldane talk about how the Silurians might be able to live alongside humans. Amy proposes using areas of the Earth uninhabitable to humans, such as deserts as new habitats for the Silurians. However, Nasreen wonders about the resources and population problem that would ensue; there're already 6 billion humans, what happens when the Silurians start reaching that number? With the promise of a place to live, Eldane insists his race can bring new technology and resources. Amy and Nasreen are pleased to hear there are benefits to sharing the Earth. As the meeting concludes, the Doctor comments on how well things have gone.

However, Rory, Tony and Ambrose enter, placing Alaya's body on the floor. Appalled, the Doctor demands to know what Rory has left happened while he was away. Ambrose tells the Doctor that she did it. Sighing, the Doctor tells Eldane that he had no idea about this; Eldane is understanding, knowing both sisters have a bigoted view of humanity and would do anything to ignite a war. Ambrose pleads that she was only trying to protect her family, but it becomes clear that even Elliot and Mo are disgusted with her.


Restac orders her troops to attack.

Restac returns and cries at the sight of her sister. She wonders why the Doctor insists they trust humans; Ambrose then reveals that drill is on a timer and that it will be disabled if the Silurians never come to the surface. When Restac learns Ambrose is responsible, she orders the woman's immediate execution. The warriors fire at her, but the Doctor steps in to protect her, using the sonic to blow up their guns. The group is forced to flee the room. Eldane leads the Doctor and his friends to the laboratory. They barricade themselves inside and try to think of a way to proceed. Time is running out before the drill reactivates and destroys the Silurian city, but with Restac's warriors surrounding them, they cannot return to the surface and turn it off. Restac's too blinded by rage to realise she'll die. Eldane decides to use an emergency failsafe called toxic fumigation. He will use the controls to release a cloud of toxic gas across the city. The Silurians in suspended animation in their cryo-chambers will be safe, but those under Restac's orders will be killed. The Doctor, with Nasreen's reluctant permission, agrees to program an energy surge to destroy the drill and prevent any further threat to the city while using the controls and his sonic screwdriver to deactivate the Silurian force field on the surface.

Though the Doctor regrets the failure of compromise, Eldane insists the Earth is not ready for the return of the Silurians yet. With this, the Doctor informs his companions that in a thousand years, the Silurians will return to the surface no matter what and they must spread the word, either religion or rumour; the Earth must be ready to accept the Silurians. Tony decides to stay behind when he learns the Silurians can cure his wound, which is causing mutation. Nasreen also opts to remain with Tony, thanking the Doctor for helping her fulfil her dream of seeing the Earth. The Doctor ushers his companions to the TARDIS, ordering the Northovers inside and telling them where the medical bay is.

Cold Blood

The Doctor forcing Amy into the TARDIS as Rory is consumed by the time field.

However, he is distracted by the sight of a crack opposite the TARDIS; Amy recognises it instantly. The Doctor is distressed that he doesn't understand it, especially when he remembers that Prisoner Zero and the Weeping Angels seemed to know what it was. Knowing that the cracks were caused by a temporal explosion, he muses that with an explosion, there is shrapnel, and reaches into the crack; wincing in pain, producing a shard of smoking debris. Before he can take a good look at it, Restac crawls into the room, having let herself be poisoned. She aims her weapon at the Doctor in revenge. Right as the Doctor is about to disable her weapon with the sonic, Rory needlessly pushes him away and takes the blast.

Before Restac can fire again, she dies. After a brief conversation with Amy, Rory dies in her arms. The Doctor, seeing Rory has already been surrounded by the time field, forces Amy into the TARDIS, where they watch as Rory is slowly being wrapped in tendrils sent out of the crack.

A devastated Amy reminds the Doctor what he told her after the Byzantium: she remembered the Clerics because she is a time traveller. This, however, is her own history changing, so it's different. He tries to help Amy remember Rory, which he admits is possible if there is no distraction. As Amy remembers Rory, her memories of him begin to fade. Amy tries her best, but the TARDIS has a bumpy landing that breaks her concentration. She forgets all about him. All that remains of Rory is the engagement ring he gave Amy lying on the floor of the TARDIS console room, and the Doctor's memories of him; the ring exists because the inside of the TARDIS exists outside of the normal time-space.

The Doctor, Amy, Elliot, Mo and Ambrose rush out of the TARDIS to see the drill explode. Sometime later, Ambrose wonders why the Doctor didn't leave her to be killed by Restac; he tells her that an eye-for-an-eye leaves the world blind, and that it's never the way. Firmly, the Doctor tells Ambrose to make up for her murdering of Alaya by making sure that Elliot grows up to be the best of humanity, which she had failed to be.

Doctor cracks origin

The Doctor makes a disturbing discovery.

The Doctor and Amy return to the TARDIS. Amy stops to wave at her future self on the opposite hill; for a moment, she believes she saw someone else next to her as well, but quickly forgets about it, reminding the Doctor of Rio. Once she is inside the TARDIS, he remembers the debris he pulled from the crack. It is a scorched blue and white fragment of wood with black lettering. The Doctor holds it against the sign on the TARDIS door, confirming it is a broken piece of the TARDIS exterior. The Doctor worriedly enters the TARDIS.


Uncredited Cast[]


General production staff

Script department

Camera and lighting department

Art department

Costume department

Make-up and prosthetics



General post-production staff

Special and visual effects


Not every person who worked on this adventure was credited. The absence of a credit for a position doesn't necessarily mean the job wasn't required. The information above is based solely on observations of the actual end credits of the episodes as broadcast, and does not relay information from IMDB or other sources.

Despite the centrality of prosthetics to creating the Silurians — and indeed the inclusion of an interview with Rob Mayor on CON: After Effects — no member of Millennium FX's staff received an individual credit on this episode.  Similarly, Davy Jones was fairly extensively interviewed in CON: After Effects, where he was clearly shown to be doing the job of the prosthetics make-up artist. However he was not credited for his work. This was the first time he was visually confirmed to be working on Doctor Who since The Parting of the WaysMalcolm Hulke did not receive a credit for creating the Silurians, though he does later on in TV: A Good Man Goes to War.


The Doctor[]

  • The Doctor asks for a stick of celery after the almost lethal "decontamination".


  • The Homo Reptilia's transport pads use gravity bubbles.
  • The Doctor looks for heat signatures to find Amy.


  • The Klempari defence is when a single member of a species claims to be the last of its kind.

Story notes[]

  • This episode was incorrectly entitled Warm Planet by the BBC. [source needed]
  • Though it apparently was not used in the episode, in Doctor Who Confidential a cut segment from the scene in which the Silurians are marching the Doctor and Nasreen to the court hall appears. In the dialogue, Nasreen expresses that she does not want to be executed "down here". The Doctor commiserates, saying that the "last time I was executed it really put a blight on the day." There are several possible events to which this could be a reference, but as this scene did not appear on screen it should not affect continuity.
  • The Doctor uses the phrase, "squeaky bum time", originally coined by Sir Alex Ferguson, the manager of football club Manchester United, in 2003.[1] Before Matt Smith became an actor, he planned to become a professional footballer, being forced out by a back injury and is still a fan of the sport.
  • This is the first episode since Part One of TV: The End of Time to have narration. Other stories with narration include TV: The Deadly Assassin, Doctor Who, Army of Ghosts and Human Nature. The opening narration, however, was not actually in the script. According to Ashley Way in the DVD commentary, it was added by Steven Moffat.
  • The Doctor mentions the Silurians going into hibernation when they predicted a planet was going to crash into the earth, which in fact was when the Moon first aligned with the Earth.
  • Clips from TV: The Eleventh Hour, The Time of Angels, Flesh and Stone, and The Vampires of Venice are shown.
  • The Doctor holds his sonic screwdriver vertically upright to disarm the Silurians, reminiscent of his older sonic screwdriver models. He was last seen to hold it like this in TV: Utopia. In Confidential, Matt Smith stated the sonic isn't a weapon, so he didn't point it at the weapons to disarm them.
  • This story continues the history of the Doctor's failure to achieve peace between the Silurians and humans. (TV: Doctor Who and the Silurians, The Sea Devils, Warriors of the Deep)
  • The actors portraying Silurians in previous stories didn't wear masks. The masks here helped save time and money since the actors wearing masks didn't require as much time in make-up. [source needed]
  • In earlier stories featuring Silurians they had a third eye which had several abilities. They could use it to generate heat to dig through cave walls, operate their technology, and defend themselves. Steven Moffat omitted the Silurians' third eye because he feared they looked too similar to Davros. [source needed]
  • Amy and Mo's discovery that the Silurians have kidnapped a menagerie of modern animals, including a dog owned years earlier by Tony Mack, was cut for time. [source needed]
  • Karen Gillan called Rory's death scene "incredibly challenging" for her to perform and tried to make it "truthful and believable". [source needed]
  • This is the first appearance of the Silurians having a long tongue that could inject venom.
  • Dropped in editing was an extensive conversation about faith between Rory and Alaya, which would have foreshadowed Rory's fate at the end of the story. [source needed]
  • Chris Chibnall wanted to give the episode a distinctive feel by changing the principal setting: after focussing on the human community of Cwmtaff in The Hungry Earth, the underground Silurian city would predominate this episode.
  • Tony Mack originally had a brother, and it was this character who murdered Alaya. However, as Chris Chibnall wrote the script, he came to feel that the strong feminine dynamic between Alaya and Ambrose Northover was more compelling; Ambrose became the Silurian's killer, and the brother was dropped.
  • This two-parter formed Block Four of season five.
  • Arthur Darvill was uncertain whether or not Rory's erasure from time meant the end of his tenure. He was booked on the show for several more months, but because the scripts were being made out of broadcast order (he was yet to record his appearances in The Vampires of Venice and Amy's Choice. Nonetheless, Darvill had heard rumours amongst the crew that Steven Moffat was not finished with Rory Williams.
  • Chris Chibnall wanted this to be a "story about people making mistakes under massive pressure" and the accidental conflict that came out of protecting a family; as such, he always intended for Alaya to die.
  • The episode utilised many different locations and unusual sets to portray the Silurian city, as the production team did not want simply a "cave feel". They believed that the Silurians were also sophisticated and were able to use materials found underground, such as granite and marble. Many of the sets were given an orange glow from beneath to portray the "ambient glow" from the centre of the earth.
  • Plantasia Botanic Gardens was chosen to portray the Silurian city, because it gave a sense of things growing, as these were necessary for the Silurians to survive. Set designers were able to rearrange the plants, though they had to be careful not to show the window leading to the car park or other modern amenities.


  • Overnight ratings were 5.7 million (5.4 million on BBC1, 0.3 million on HD) for a 27.2% share.[2]
  • Official viewing figures was 7.04 million.
  • Final UK ratings were 7.49 million.[3]

Filming locations[]

Production errors[]

If you'd like to talk about narrative problems with this story — like plot holes and things that seem to contradict other stories — please go to this episode's discontinuity discussion.
  • In particular close-ups, one of Restac's 'scales' is absent, leaving an obvious hole where it should be in Neve McIntosh's prosthetics.
  • When running from the Silurians in the tunnels, the Doctor holds his sonic screwdriver. In the shots of the Doctor, the screwdriver is vertical, but in the shots of the Silurians, the screwdriver is more horizontal.
  • At one point, the Silurian city's computer states that the toxic fumigation is about to begin and everyone needs to evacuate as the Doctor's group runs. However, the fumigation has already begun as evidenced by the toxic gas shown being released moments before the announcement.
  • When Amy is trying to not forget Rory, the memory of him getting shot does not show the laser blast striking him.
  • When Restac shows up, the Doctor has just pulled the shard of the TARDIS out of the crack. He starts to push himself off the ground. The camera cuts to Restac dragging herself towards them and then back to the Doctor, who finishes jumping to his feet. The shard of the TARDIS is nowhere in sight. It has not been left on the ground and there wasn't time for the Doctor to put it in his pocket.
  • In the scene where Rory is dead after the Doctor remembers about the crack erasing people, he goes near the TARDIS, but when it cuts to Amy crying, the Doctor is behind her. There wouldn't be enough time for him to go from the TARDIS to behind Amy.
  • When saving Ambrose from a Silurian ray gun, the humans run from the Silurians. Tony is seen directly in front of the Doctor and Elliot. However, in the next shot, he is at the front of the group, directly in front of Nasreen.


Home video releases[]


Series 5, volume 3 DVD cover

DVD & Blu-ray releases[]

  • Series 5, Volume Three was released on DVD and Blu-Ray in region 2/B on 2 August 2010 and region 4/B on 2 September 2010. The volume features Amy's Choice, The Hungry Earth and Cold Blood, and the featurette The Monster Diaries.
  • The episode was later released in the Complete Fifth Series boxset on both DVD and Blu-ray, in region 1/A on 9 November 2010, in region 2/B on 8 November 2010 and in region 4/B on 2 December 2010.
  • A DVD-only release of Series 5, Part Two, containing the latter seven episodes of the series, was released in region 1 on 26 July 2016.

Digital releases[]

  • In the United Kingdom, this story is available on BBC iPlayer.

External links[]