Nightmare in Silver (TV story)

Nightmare in Silver was the twelfth episode of the seventh series of Doctor Who produced by BBC Wales. This adventure introduced a dramatic evolution to the Cyberman race that replaced the previous design they had maintained since their return in Rise of the Cybermen, employing a multitude of new abilities, including that of being able to convert species other than humans, this effectively reintroduced the Cybermen of the Doctor's universe for the first time since the series started back in 2005. Likewise, the Cybermats evolved with their progenitors into a more compact form known as Cybermites. Additionally, the Cybermen utilised a Cyber-Planner for the first time onscreen in the revived series, last seen in The Invasion. The episode also saw the introduction of "Cyberiad", the collective consciousness of all Cybermen.

This episode also allowed actor Matt Smith to undertake a dual role against himself in a "Jekyll and Hyde" scenario, as the Eleventh Doctor battled an evil Cyberman alter-ego, Mr Clever.

Synopsis
The Eleventh Doctor takes his companion, Clara Oswald, and her wards, Angie and Artie, to the biggest amusement park, Hedgewick's World of Wonders. The theme park is empty, occupied by a "punishment platoon" and a lone impresario with empty Cyberman shells as exhibits. The Doctor decides to stay a while, however, to investigate strange insect creatures that are roaming the park. But these insects are really machines seeking to convert the life forms on Hedgewick's World into the newest generation of the ever-upgrading menace...

Plot
The TARDIS lands and the Eleventh Doctor, Clara, Angie, and Artie Maitland step out. The Doctor welcomes them to Hedgewick's World of Wonders, the biggest and best amusement park ever. Though Clara and Angie look sceptical, the Doctor repeats that it's not the Moon. Suddenly, a rock opens and a short man in a top hat peeks out. A shout goes up and the man disappears. A military platoon comes storming out and demands identification from the travellers. The Doctor flashes his Golden Ticket, and when that doesn't work, whips out the psychic paper. The captain recognises him as the Imperial Consul, and asks for news of the Emperor. The Doctor dismisses the platoon, and the top-hat man comes out again. He leads them into the desolate, formerly grand amusement park, and then into his attraction: Webley's World of Wonders.

He introduces himself as Impresario Webley, and shows them his waxwork attractions of beings. He asks Artie for a game of chess, and leads him to a Cyberman at a chess board. The Doctor yells to get down as the Cyberman powers up. Webley reassures them that it's completely harmless. He cites his display as "the six hundredth and ninety-ninth wonder of the universe", and a master at chess, despite the fact that it is an empty shell. He offers five Imperial shillings for a penny if Artie can beat the Cyberman at chess. Artie offers a sandwich, and Webley accepts. He shows that the shell is free of all devices. Webley offers a silver penny to Angie if she can figure out how it works. She guesses that it's done with mirrors. The Doctor deduces that it's being controlled by a man inside the box, named Porridge, and Webley gives Angie a silver penny. Webley shows off the rest of his Cyberman collection, as well as a wax figure of Emperor Ludens Nimrod Kendrick Cord Longstaff XLI, Defender of Humanity and Imperator of Known Space. The adults lead the kids off to the Spacey-Zoomer ride. The Spacey-Zoomer ride turns out to be an anti-grav ride, letting the children fly and float around. Clara wants to get the kids home, but the Doctor doesn't want to leave. He finds "funny insects" that he wants to investigate, and forces everybody to stay longer. The kids crash on couches in Webley's house, and adults go off, with the Doctor warning the kids not to wander off. The terrified kids settle into the couches.

Webley resets his chess board while eating the sandwich he won off of Artie. Suddenly, the Cyberman grabs him and Cybermites begin upgrading Webley. Meanwhile, Angie declares the future to be stupid, complaining that there isn't even phone service. She leaves, despite protests from Artie, as the insects crawled over Clara's phone. Elsewhere, Porridge explains the Cybermen to Clara. He tells her of the Tiberian Spiral Galaxy, which had to be blown up to destroy the Cybermen. Porridge comments that he feels like a monster: instead of mourning a billion trillion deaths, he feels sorry for the person who had to press the button. The Doctor interrupts and asks Clara if she told Angie she could go to the barracks. Clara realises that Angie had wandered off. In the barracks, the platoon are trying to fix their systems, when Angie appears. The captain asks Angie where her sister was. Realising that she meant Clara, Angie denied that they were sisters, calling Clara stupid and saying she was talking to Porridge (the captain mistaking this as Clara talking to a real porridge). The captain pulls Angie off for a talk.

Meanwhile, Artie wanders off, looking for a light switch. He finally finds the lights. Suddenly, a Cyberman abducts him. At the barracks, Angie is telling the captain about Porridge when Clara storms in. Without warning, an upgraded Cyberman appears in the doorway. The Cyberman, able to move faster than their eyes can follow, captures Angie and escapes. Clara tries to go after Angie, being stopped by the Doctor. He promises that he will get her back. The Doctor invokes his "power" as "Imperial Consul", stripping the captain of her rank and giving it to Clara. He tells Clara not to let them blow up the planet, to get to somewhere defensible, and to stay alive. The Cyberman brings Angie to a room, where she finds her brother controlled by a Cyber earpiece.

Meanwhile, Clara, in her new role as commander, scrounges up all their resources to build an offence against the Cybermen. They decide to move to Natty Longshoe's Comical Castle for defence. The captain informs Clara that the platoon can deal with one Cyberman, but there are protocols that they must follow if they cannot find and destroy it: specifically to blow up the planet. Clara rejects this and orders the platoon to move to the castle. The Doctor returns to where he left the children, finding them missing. He spots a cyber insect on a display. Regarding it, he informs whoever is watching the feed that the children are under his protection, and he is coming to get them. Then he informs the machine that "[it] is beautiful!", sonics it, and studies it. He uses the sonic to tune into the local transmat, bringing himself to the children. He realises what has happened to them and Webley. His brain fully converted, Webley speaks for the Cybermen. He informs the Doctor that they needed children, and declares him the "saviour of the Cybermen".

The platoon approaches the castle, and the captain tries to convince Clara to blow up the planet. Clara declares that the only reason she was alive is because she listened to the Doctor.

Webley tells the Doctor of the Cybermen. As the battle raged between humanity and the Cyberiad, they built a bunker to repair their damaged units. They needed children's brains to build a new Cyber-Planner, as a child's brain has infinite potential. However, now that the Doctor is there, they have no need of the children. The Doctor scoffs, telling them that they can only convert humans. Webley tells him that that is no longer true. He throws Cybermites on the Doctor, which incorporate him into the Cybernetwork. He becomes the Cyber-Planner, with non-human brain power to dream up ideas to strengthen the Cyberiad. He takes stock of his body, noting the unfamiliar systems and remarkable brain power. Inside the Doctor's mind, the two meet. Rather in a Jekyll and Hyde manner, the two wage war for control, the Cyber-Planner using his memories to torment the Doctor.

The Cyber-Planner finds delight in his cleverness, realising that there is information on the Time Lords available. The Doctor blocks it all but information on regeneration. He threatens to regenerate right then and there, to burn out the Cyber-Planner. He doesn't want to, unsure of what he'll end up with next, but acknowledges that he could do it. The Cyber-Planner declares a stalemate, concluding that they are too well balanced. One must take over. Each controls 49.881% of the brain, leaving .238% unclaimed. The Doctor challenges the Cyber-Planner to a game of chess; winner takes all. If the Cyber-Planner wins, he gets the Doctor's mind. If the Doctor wins, he gets his mind back, the children are freed, and nobody dies.

Missy takes guard of a corridor. She notices a shadow, and reports it as possibly a Cyberman. The Cyberman detaches its hand, which crawls over to Missy and drags her out of her hiding place. Back at base, the platoon realise that the Cyberman is on its way. Clara demands to be shown all weapons. There is only one anti-cyber gun. She is shown hand pulses, which are able to disable a Cyberman on contact. Finally she is shown the weapon which can implode the planet. Clara takes the remote control from the captain, but the captain informs her that it is set to respond to her voice only. Clara orders her to detonate the device only when she directly orders her to. The captain challenges Clara's command, but Clara asserts her authority and signs for the remote control.

The Doctor and the Cyber-Planner begin their game. While they play, the Cyber-Planner asks the Doctor why the Cyberiad has no record of him. He then realises that the Doctor purposely erased himself from history, noting that he could be reconstructed from the holes he left. The Cyber-Planner rails against him, telling the Doctor that he cannot win against him. The Doctor counters with his knowledge of early Cybermen. Their codes can be scrambled by cleaning fluids and gold. He then slaps his Golden Ticket on the the metallic growth on his face, temporarily scrambling the circuits. He comes back to himself, collects the chess board, and brings the children and Webley to another room.

The captain and Porridge are discussing a secret regarding Porridge. She talks about guarding the old Emperor, and how she knows. Clara interrupts, asking why it was necessary to blow up a whole planet just to get rid of one Cyberman. Porridge says there are ways to kill a Cyberman, but they don't always work. Blowing up the planet is the only surefire way to do it. The captain says that she was sent to the punishment platoon because she didn't follow orders, and that she can make up for it now. She declares that she will do what she was born to do: fight for the Empire. She begins to voice-activate the weapon but is shot by a Cyberman. Clara decides to go on the offensive, otherwise facing death. The platoon mobilises with hand pulses and the anti-cyber gun. The members of the platoon launch sneak attacks on the Cybermen, with limited success.

The Doctor approaches the castle with the children and Webley in tow. Clara comes out with the anti-cyber gun and the Doctor greets her. The Doctor rattles off his news: he kidnapped the Cyber-Planner, which is in his head. The kids are in a walking coma, which he may or may not be able to correct. There are more Cybermen active, and the Cyber-Planner is installing a gold patch. He asks for a table and for somebody to immobilise him (except for his hands). Once tied up, the Doctor removes the gold sheet from his face. The Cyber-Planner reemerges, taunting Clara. As the Cyber-Planner continues to rattle on, the Doctor moves his hand, writing "HIT ME!" on the notepad beside the chess board. Clara obliges. The Doctor thanks Clara, who demands to know the stakes. The Doctor elaborates that the Cyber-Planner will probably break his promise. Clara begs the Doctor to fix Angie and Artie. He says that they're just in standby mode. He then explains that they are more likely to leave alive than she is. Sensing the change in control, she surmises that the Cyber-Planner said those words. He threatens her immediate death, and she leaves to prepare the platoon for the coming onslaught.

Clara discusses their weapons, which are minimal at that point. Spotting a cable, she cleverly devises a plan to electrify the water in the moat. They drop the cable into the water, turn on the power, and raise the drawbridge to force the Cybermen to cross the water.

The Doctor's game continues. Inside his mind, the Cyber-Planner awakes the legions of Cybermen hidden in the barracks. Inside the citadel, the platoon prepares their defence. The Doctor calls for Clara, and she goes to check on him. The Doctor cheerfully asks her for a rundown on their weapons, with keen interest in the planet-imploding bomb. She shows him the remote trigger, which he tries to take possession of. She snatches it away from him, suspicious of who really is in control. The Doctor says the Cyber-Planner is hibernating, but Clara doesn't buy it. She tells him to tell her something only the Doctor knows. Looking rather sincere, the Doctor begins to tell her that he is falling in love with her. He moves to kiss her, but Clara slaps him again. The Doctor comes to himself, overtaking the Cyber-Planner's tricks. Clara tells him to finish the game, and the Cyber-Planner grabs her hand, wresting the remote control from her and destroying it. Clara and the platoon ready their attack with the five hand pulses and the nearly empty anti-cyber gun. The Cyber-Planner declares endgame and moves to finish the Doctor. The Cyberarmy begins to assault the castle. One steps into the moat and is apparently electrocuted. The platoon celebrates, but then the Cyberman upgrades itself. The patch is spread through the ranks, and the Cybermen continue onward. Clara gives orders to defend the castle, and tells Porridge to keep himself safe. Two soldiers shoot down the first Cyberman, but balk as more come through. Porridge grabs the bomb, muttering that he should have destroyed the planet when he had the chance.

The Cyberplanner taunts the Doctor, offering him one more deal. If the Doctor sacrifices his queen, the Cyberplanner will release the children but win the game in five moves and take the Doctor's mind. The Doctor accepts the deal and Angie and Artie are released. The Doctor appears to have lost, but the children are free. The Cyberplanner taunts him once more, telling him how foolish he was to have pointlessly sacrificed himself for two human children. He mockingly asks the Doctor if he thinks that the death of the children will affect his relationship with Clara. Webley moves to kill the children, but Porridge slaps a hand pulse onto his leg and kills him. Angie awakes and the Doctor tells her to look after Artie.

The platoon are losing the battle. They are out of weapons, and the Cybermen's continual upgrades are proving to be more than a match for the ragtag soldiers. The Doctor taunts the Cyber-Planner, telling him that sacrificing his queen was the best move he could have made. The Time Lords invented chess, and the Doctor has cleverly set up a trap that will give him checkmate in three moves. The Cybermen appear to be overwhelming the platoon, but as they are about to deliver the killing blows, the Cyber-Planner pulls in their resources, giving him extra processing power to figure out and counter the Doctor's strategy. It saves the lives of Clara and the rest of the platoon, but puts the Doctor at a serious disadvantage. As the platoon makes their last stand, the Doctor begins his endgame. Move One: Turn on sonic screwdriver. Move Two: Activate pulse. Move Three: Apply pulse. With some resistance from the Cyber-Planner, the Doctor slaps himself with the hand pulse and destroys the Cybercircuitry in his body.

Clara rushes in to find the Doctor completely back to himself and unties him. The Doctor decides that they need to blow up the planet to destroy the Cybermen. This seems impossible since the captain is dead, but Angie deduces that Porridge can voice activate it, since he is the Emperor. Porridge confirms it and activates the Desolator, just as the Cybermen begin to regain their mobility. The Imperial ship warp-jumps them from the planet, including the TARDIS. The bomb ticks down, and the planet blows up, taking the Cyberiad with it. Porridge remarks that he liked being normal: not an emperor of a thousand galaxies, not lonely. Clara says that he doesn't have to be lonely, and he agrees, proposing to her on the spot. The Doctor attempts to interrupt, but is shushed by Clara, who prompts the Emperor to continue. Porridge makes a convincing argument, to which Clara declines gently. Angie calls her stupid for not saying yes, loudly declaring that one day, she'll be queen of the universe. Porridge pretends to threaten them with execution, before mirthfully telling them to leave.

The Doctor returns the children and Clara to their home, pondering Clara's identity once more. Back on the imperial ship, the Emperor asks if there was any Cybertech remaining. With the answer being no, the Emperor then flies his ship home — with a floating Cybermite blinking in the darkness of space.

Cast

 * The Doctor - Matt Smith
 * Clara - Jenna-Louise Coleman
 * Angie - Eve De Leon Allen
 * Artie - Kassius Carey Johnson
 * Webley - Jason Watkins
 * Porridge - Warwick Davis
 * Captain - Tamzin Outhwaite
 * Beauty - Eloise Joseph
 * Brains - Will Merrick
 * Ha-Ha - Calvin Dean
 * Missy - Zahra Ahmadi
 * Cyberman - Aidan Cook
 * Voice of the Cybermen - Nicholas Briggs

Alien species

 * Waxworks sculpted in the likeness of a Shansheeth, an Uvodni head, the upper body of a Blowfish, a creature resembling a Gastropod, a Ventriloquist Dummy of the like seen previously in The God Complex, an Ultramancer, a Pan-Babylonian and a Lugal-Irra-Kush can be seen on display inside the room housing the chessboard.

Cybermen

 * The Cyber-Wars ended 1,000 years ago. The planet where Hedgewick's World is situated was used to hide 3 million Cybermen and repair them.
 * Whilst not being able to convert non-humans in the past, the Cybermen can now process creatures like Time Lords, at least partially.
 * The "Cyberiad" refers to the collective consciousness of the Cybermen.

The Doctor

 * Whilst under possession by the Cyber-Planner, the Doctor mimics the Ninth Doctor's accent and catchphrase of "Fantastic", as well as the Tenth Doctor's of "Allons-y".
 * In addition to his binary vascular system, the Doctor has a hyper-conductive nervous system and "remarkable brain processing power", according to Mr Clever.

Clara

 * The Doctor and Clara meet on Wednesdays for their adventures.

Games

 * The Doctor claims that the game of chess was invented by the Time Lords.
 * Artie Maitland plays chess versus the "Cyberman" (Porridge) and accidentally commits a Fool's mate.

Story notes

 * The working title for this episode was The Last Cyberman.
 * The ending of the story, in which a lone Cybermite is seen drifting into space, having escaped the destruction of the planet, is reminiscent of the end of TV: Tomb of the Cybermen, in which a single Cybermat escapes from the tombs just before they are sealed.
 * Subsequently, the Cybermen exiting their tombs mirrors the cliffhanger of Earthshock Part 3 when three rows of Cybermen march towards the camera. It's also very similar to the scene where the Cybermen come out of their tombs in The Tomb of the Cybermen.
 * The Doctor also had a conversation with himself in another Cybermen-story. (TV: The Moonbase)
 * The Doctor threatens to regenerate to eliminate all traces of Mr Clever from his body, though it's later revealed that this was actually a bluff. (TV: The Time of the Doctor) However the Doctor could have been threatening to commit suicide, like Azmael. (TV: The Twin Dilemma)
 * The scene where Porridge operates a Cyberman exoskeleton in a game of chess is a homage to the Turk, an animatronic man that was purported to be a chess-playing automaton (an animatronic capable of completely independent motion). In reality, the Turk was operated from within by a human chessmaster, not unlike Hedgewick's "Cyberman." The Turk previously served as an inspiration for the stories TV: The Girl in the Fireplace and AUDIO: The Silver Turk.
 * This is the eleventh time the actor playing the Doctor has portrayed a different character in the same story - although in this case only, the Doctor and the other character physically inhabit the same body. Other dopplegangers previously were seen with:
 * William Hartnell (The Chase and The Massacre of St Bartholomew's Eve)
 * Patrick Troughton (The Enemy of the World)
 * Tom Baker (The Android Invasion and Meglos)
 * Peter Davison (Arc of Infinity and The Caves of Androzani)
 * David Tennant (Journey's End)
 * Matt Smith (The Almost People and The Wedding of River Song)


 * When the Doctor lets the Mr Clever access his memories on regeneration, the First, Second, Third, Fourth, Fifth, Sixth, Seventh, Eighth, Ninth and Tenth Doctor are seen. Each image is taken from photograph stills used as promotional material during the respective actors' tenures. All of these images can be found on the banner of the Doctor Who BBC America website.
 * According to "Behind the scenes...", the Cybermen were redesigned for this episode and got a variety of new abilities and features. These new Cybermen share several similarities with the Borg of Star Trek franchise - which were in turn originally based somewhat upon the Cybermen. The Cybermen's ability to adapt to attacks is reminiscent of the Borg from Star Trek: The Next Generation. Additionally, the Borg used nanoprobes to convert individuals, similar to the cybermites, and Webley's cyber-appearance is reminiscent of the Borg's "half machine, half human" face. And as of "" they, like these Cybermen, assimilated new members by use of something coming out of their wrists. Voice notifications for individuals to convert were also typical for the Borg and the Cybermen, both new and old.
 * The Cyber-Doctor says "Fantastic" like the Ninth Doctor, and says "Allons-y" like the Tenth Doctor.
 * The converted Webley tells the Doctor that the Cybermen had turned children into Cyber-Planners in the past because of a child's imagination. This mirrors the reasoning behind the Renegade Daleks' use of a young girl as their Battle computer in Remembrance of the Daleks.
 * This episode uses a camera technique known as "Bullet Time", popularised in the science fiction film The Matrix to frame out the high-speed movements of the new Cybermen, as shown in the "Behind the Scenes" featurette for Nightmare in Silver.
 * The Cyber-Planner makes its first appearance within the revived series. However, this is not the first time it has been incorporated into the elements of the revived timeline. Cyber-Planners previously appeared in GAME: The Eternity Clock.
 * This is the fourth time that an actor playing the Doctor portrays the primary antagonist of a story alongside their incarnation of the Doctor. The earlier instances occur in The Enemy of the World, Meglos, and Arc of Infinity (although the latter only included this development in the final episode).
 * This is the third consecutive series' penultimate episode where the Cybermen have been featured, after The Pandorica Opens and Closing Time.
 * When Clara asks for proof that he's the real Doctor, he answers by insulting her appearance. This is the only time the Eleventh Doctor does so on screen, but it becomes a running gag with the Twelfth Doctor during Series 8.
 * The Emperor calls himself "Porridge", which is a character in the British sitcom of the same name. In the show, Porridge is in jail. "Doing porridge" is British slang for serving a prison sentence, porridge once being the traditional breakfast in UK prisons.

Ratings
Overnight viewing figures estimate that the episode was watched by 4.7 million viewers, rising to 6.64 million after calculating the final ratings, making it the ninth most-watched programme of the week on BBC One.

Filming locations
to be added

Production errors

 * When the Doctor was running to the castle, the gold ticket he used to shut down the Cyber Planner is missing from his face. However, when he encounters Clara and the Platoon, the ticket is on his face again.
 * One of the Cybermen's chestplates is pushed up, most likely due to it being too short for the actor wearing it.

Continuity

 * The Doctor can play chess. (TV: The Sun Makers, The Androids of Tara, The Curse of Fenric, The Wedding of River Song). Also, the Time Lords inventing chess was a query first considered by the Second Doctor. (PROSE: Dreams of Empire)
 * This is not the Doctor's first encounter with a Cyberman purported to be an automated game-playing machine. When the Eighth Doctor encountered the Silver Turk, a Cyberman, it too attacked its 'controllers'. (AUDIO: The Silver Turk)
 * The Doctor mentions and exploits the Cybermen's weakness to gold (TV: Revenge of the Cybermen, Earthshock, Silver Nemesis) and cleaning fluid. (TV: The Moonbase)
 * Two impact suits can be seen. (TV: The Doctor, the Widow and the Wardrobe)
 * The Doctor says the children are under his protection. (TV: The Bells of Saint John)
 * Angie and Artie Maitland travel in the TARDIS, as they had previously blackmailed Clara into taking them along. (TV: The Crimson Horror)
 * The Doctor shows Mr Clever the memory of his most recent regeneration. (TV: The End of Time).
 * When talking about the Doctor to Clara, Mr Clever says that he's "had some cowboys in here". The Tenth Doctor used this phrase to describe the state of the ship SS Madame de Pompadour. (TV: The Girl in the Fireplace) The Eleventh Doctor also said this to young Amelia Pond. (TV: The Eleventh Hour)
 * Mr Clever seems excited to get knowledge of the Time Lords, whereas earlier in their history, the Cyber-Leader considered the secrets of the Time Lords to be of no concern to the Cybermen. (TV: Silver Nemesis)
 * Several wax replicas of creatures are seen in Webley's room. This includes an Uvodni head, (TV: Warriors of Kudlak) a Blowfish head, (TV: Kiss Kiss, Bang Bang) a Shansheeth head, (TV: Death of the Doctor) a Chameleon, (TV: The Faceless Ones) a dummy, (TV: The God Complex), an Ultramancer, a Pan-Babylonian and a Lugal-Irra-Kush (TV: The Rings of Akhaten).
 * The Doctor previously visited an amusement park "controlled" by aliens. (TV: The Greatest Show in the Galaxy)
 * Angie's mobile phone has no service, indicating that the Doctor didn't give her a superphone, as he had with every one of his regular companions since his ninth incarnation. (TV: The End of the World, 42, The Doctor's Daughter, Dinosaurs on a Spaceship) She is given a new phone "from the TARDIS" at the end, although it isn't clear whether or not this is a superphone.
 * The Doctor says to the Cybermite, 'Not even a Cybermat'. (TV: The Tomb of the Cybermen, Revenge of the Cybermen, Closing Time)
 * The Doctor echoes a quote from his former companion Rory Williams when confronted by the troops aiming guns at him: "Don't shoot, I'm nice!" (TV: The God Complex)
 * The Doctor's defeat of the Cyber-Planner, distracting him with a bluff about an alleged checkmate to drain his power, is the same stratagem he used against Fenric in his seventh incarnation. (TV: The Curse of Fenric)
 * The Doctor refers to an enemy, the Cybermite, as "beautiful." (TV: Tooth and Claw, The Girl in the Fireplace, The God Complex, PROSE: Dark Horizons)
 * Webley claims that the Chess playing Cyberman is the 699th Wonder of the Universe. The Third Doctor claimed the destruction of the Exxilon City brought the universe down from 700 to 699 Wonders (TV: Death to the Daleks).
 * UNIT also designed a device that would blow up a planet to be used if left with no other options, the Osterhagen Project. (TV: The Stolen Earth/Journey's End)
 * The Doctor and Mr Clever discuss the Doctor removing himself from databanks across the universe. (TV: Asylum of the Daleks, Dinosaurs on a Spaceship, The Angels Take Manhattan)
 * The Doctor says that the Cybermen can't convert non-human beings. However, in his sixth incarnation, he met Cybermen who, whilst in the Land of Fiction after Zoe Heriot piloted them there, converted Fairies, Trolls, Mermen, Vampires and even a Whale into their Cyber-forces. (AUDIO: Legend of the Cyberman)
 * This is the third consecutive penultimate episode to prominently feature Cybermen. Every next-to-last episode of a series featuring the Eleventh Doctor has done so. (TV: The Pandorica Opens, Closing Time)
 * Porridge's title of Imperator is similar to a title Imperiatrix on Gallifrey which Pandora and the Doctor's former companion Romana held. (AUDIO: Lies, Pandora to Appropriation)
 * The Doctor's body being possessed by a villainous being that makes him appear to be an evil version of himself is similar to the instance where the Ninth Doctor had his body overtaken by an entity in COMIC: The Cruel Sea.
 * The Tenth Doctor also considered regenerating to rid himself of a being who was possessing him. (TV: 42)

DVD Releases
Nightmare in Silver was released as part of Doctor Who Series 7 Part 2 on May 22, 2013, and as part of The Complete Seventh Series on September 24, 2013.

Blu Ray releases
to be added