The one with Sigma. Theta Sigma. And the one with the O Crap! moment of the century.
Written by Chris Chibnall, who described it as the "biggest episode ever", this two-episode serial originally aired from January 1-5, 2020. It is the first story in the Revival Series to consist of numbered parts since "The End of Time" in 2009-2010.
Part 1Across the globe, intelligence agents in the Ivory Coast, on a plane over the Pacific Ocean, and in Moscow are all targeted by mysterious creatures that can phase through walls. In Sheffield, Ryan, Yaz and Graham are all at home: Ryan playing basketball with his co-workers from his warehouse job, who wonder at the litany of medical problems he's had over the past months; Yaz, packing and heading off for another undercover job as her sister tries to get Ryan's number and her boss despairs; and Graham finishing up a medical appointment. All find themselves met by black cars, driven by men in black suits and sunglasses. At a garage, the Doctor is working on the TARDIS — draining water out of slides, lakes and a rainforest that are somewhere inside — and wondering why her "fam" is late when the three cars arrive to pick her up.
The Doctor would like to know where everyone is being taken, but before she can get an answer the SUV she and her friends are passengers in is remotely hijacked, with the driver disintegrated. Once the Doctor manages to stop the vehicle in the nick of time, a voice on the radio demands to know who's wrecking his cars. The voice belongs to C, head of MI6, and the Doctor agrees to come over, driving herself, to see what he wants. After some identity-related confusion, C shows the Doctor and her companions a woman hooked up to medical apparatus; one of his agents, found unconscious in an airplane washroom after making pre-arranged contact with an informant. He has been granted the authority to speak for all of Earth's intelligence agencies, all of whom are losing people. All of the attacked agents were investigating leads related to tech billionaire Daniel Barton, head of Mega-Corp VOR.
The Doctor and her companions agree to help, with Ryan and Graham awed by the various spy gadgets they're shown. However, the Doctor is incredulous that C dismissed Horizon Watcher, the agent responsible for monitoring extraterrestrial threats, especially since groups like UNIT and Torchwood are no longer active to keep Earth safe. C can't even find Horizon anymore, since he's gone off the grid, but the Doctor has been keeping in touch. When the conversation returns to Barton, it transpires that he was once an MI6 agent, but eventually stopped cooperating with them after he moved to America, and C suspects he may have turned double or even triple agent. The Doctor asks him who he thinks Barton works for now, but a laser shot through the window behind him puts him down before he can answer. The phasing creatures attack, and the Doctor and her companions flee into the TARDIS with the cases of gadgetry. One of the creatures, to the Doctor's shock, nearly manages to get through the TARDIS's doors before she shakes it by taking off, and afterwards the sonic can't get a read on anything.
The fam decides to split up: Ryan and Yaz are sent to San Francisco to see Barton and scan for any data they can find. Meanwhile, the Doctor and Graham head to the Australian outback to pay a visit to the Horizon Watcher and see if he's got any information. Yaz and Ryan use the stash of gadgets to pose as reporters Sofia Afzal and Logan Jackson, using camera attachments and a bioscanner disguised as a digital recorder during their brief interview. After Barton is called away early, he invites them to his birthday party the next day as a consolation prize. When Yaz checks the scanner, she discovers that Barton's DNA reads as only 93% human. In the Outback, the Doctor and Graham arrive at a remote house to be greeted by Horizon Watcher, a former MI6 agent codenamed "O", and Seesay and Browning, two ASIS agents who've recently been assigned to guard him due to the threat.
O's house is full of information and computers. He's rather paranoid, or as he prefers, cautious, due to the alien threats he researches and keeps an eye on. He notes that, given the threat, it's possible some of them might follow the Doctor all the way out here. In San Francisco, Yaz and Ryan sneak back into VOR headquarters after hours using a duplicate of Barton's pass to steal files from his computer. They have a near miss when Barton unexpectedly returns, but they manage to finish the download and hide before he enters. Barton has a meeting with two of the intangible creatures, and he is not happy about them being less discreet than he'd like. After he leaves, Yaz tries to look for more leads but is unexpectedly ambushed by one of the creatures and vanishes, causing Ryan to flee. Yaz finds herself in a dark, misty place with cable-like pillars all around and lights moving through them into the ground. Ryan watches from outside as dozens of glowing figures appear in the windows of the VOR building.
Down Under, as night falls, creatures approach and begin to set off O's security. Since the Doctor still can't detect them, she surmises that they're intentionally making their presence known. The ASIS agents are attacked and vanished by the creatures, but O is able to use his security systems to drive off all but one of them before they can enter the house. When the remaining creature gets inside the house, the Doctor and O are able to trap it in a cage he had rigged, diverting power from the energy fence to trap it inside. The creature eventually speaks after multiple questions from the Doctor, saying only that it and its kind desire to control this universe and that they take their humanoid form to mock humanity. The creature then glows brightly and eventually vanishes from the cage, with Yaz left in its place. Ryan calls the Doctor to tell her Yaz is gone, but she reassures him that Yaz is safe before heading off to fetch him from the US.
After being brought to O's house, Ryan comforts a shaken Yaz. Talking with O inside, Graham is surprised to learn that the Doctor's claim of once having been a man wasn't just something she was joking about. O offers to show Graham his files on the Doctor, but before Graham can decide whether to accept, the Doctor pops in with a pitcher of iced tea and everyone heads out to the porch for some data analysis. Barton's non-human DNA is brought up, but the idea that a man as photographed as him could be a fake identity is dismissed as implausible. The Doctor discovers some alien code in the stolen data, and upon translating it, it turns out to be an encrypted image much like the one O sent the Doctor earlier, containing a map of the Earth charting the locations of the light creatures. Actually, it's multiple maps, but the Doctor can't figure out what they mean. So the Doctor and her friends decide to infiltrate Barton's birthday party. With everyone but Yaz kitting themselves out in tuxedoes from the TARDIS wardrobe (PC Khan going for a different choice of formalwear), they enter Barton's vineyard estate. As the companions enjoy themselves at the tables, since the party has a gambling theme, Barton and one of his staff note Ryan and Yaz, who failed to erase themselves from the office security footage.
Eventually, the Doctor manages to get Barton alone and asks him several pointed questions about what's going on, all of which he denies. He eventually orders her to stay away from him before leaving, and the Doctor and her friends chase after him. When Barton leaves in a car driven by a chauffeur, the Doctor and company steal motorcycles to follow. After a chase through the vineyard, during which Barton shoots a pistol at them, Barton disappears into a hangar. The Doctor and company follow him to the plane he's had readied for takeoff, and enter via the cargo hatch as the plane is preparing to take off. But as the plane reaches altitude, the Doctor realizes something's off. O said he wasn't good at sprinting after he got on the plane, but the files she read about him said he was a champion sprinter...
Yes, you can't have Bond without Blofeld, as O is not who he said he is. O had told the Doctor to look for the spymaster, or in this case, spyMaster. Indeed, the "O" really stands for Oh, Crap! it's The Master, as Gallifrey's resident deranged nutjob is back once again, having intercepted the real O on his first day at MI6 before pulling out the ol' Tissue Compression Eliminator, keeping his shrunken corpse in a matchbox in his pocket, going the Tremas route and pulling a Kill and Replace.
The companions don't know what this means, but the Doctor is very, very scared. And it turns out Barton has vanished from the plane, replaced by a bomb that the Master announces he's deadlock-sealed so she can't stop it from detonating. He's also arranged for there to be no parachutes. One of the glowing creatures appears and, on the Master's command, vanishes the Doctor right after her archenemy informs her that "everything you think you know is a lie". The Doctor finds herself in the same nowhere-place that Yaz was trapped in as the Master teleports off the plane, leaving Ryan, Graham and Yaz on the stricken aircraft as it plummets from the sky, cockpit destroyed by the bomb...
Part 2We pick up right where we left off, with the Doctor attempting to get her bearings in the nowhere-place, and her fam plunging to their doom. But the Doctor finds that she is not alone, finding a woman in 19th century dress who is strangely calm in the bizarre landscape. She introduces herself as Ada Gordon, and says that she has been brought here multiple times by her "guardian", one of the alien spies. Ada says that the creature will return her home and can bring the Doctor with her. The Doctor is suspicious, but takes Ada's hand as the creature glows brighter.
Meanwhile on the plane, Ryan discovers a series of unusually well placed notes guiding him to directions to pilot the plane, as well as a video from the Doctor attempting to talk them down, before a malfunction shorts out the video. Fortunately, Ryan is able to use the directions to access the plane's computer, leveling it out and bringing it in to land. Unfortunately, while travelling in the Master's TARDIS, Barton is informed that his plane is coming in for a landing, and the TARDIS has detected the Doctor. Furious, the Master sends Barton to deal with the companions, while he goes after the Doctor.
The Doctor and Ada materialize in the middle of the Adelaide Gallery in London 1834, where various inventors are displaying their wares. The Doctor is able to play off her and Ada appearing out of nowhere as a trick, but she is now trapped in the 19th century without her TARDIS or her friends. Meanwhile, in 21st century Essex, Ryan, Graham, and Yaz hide from Barton at the airport, determined to carry on finding out what Barton and "O" are planning. Using information from hacking Barton's diary, they set out for London to follow Barton to a keynote address he will be giving.
Back in the 19th century, the Doctor tries to explain the situation to Ada, but is interrupted by the Master, who starts using his Tissue Compressor Eliminator on the visitors. He forces the Doctor to kneel before him, but the Doctor realizes that the Master does not completely control the aliens (the Kasaavin). The Master teases "news from home" before Ada starts using the weapons on display to injure him and force him to retreat.
In the 21st century, Barton uses his contacts to locate Ryan, Graham, and Yaz, framing them for the destruction of the plane and putting anyone they know under surveillance. Graham is able to guide them to a construction site to hide out, where they express their concerns about the Doctor; not just about whether she's alive but why she didn't tell them more about her past. After Yaz remarks that the Doctor clearly knows "O" but somehow didn't recognize him, the companions put pieces of information together (the Doctor mentioning that she used to be a man, what she told Graham and Grace about the night they met) and deduce what regeneration might be. On the plus side, Ryan and Graham are both wearing some of the spy gadgets from C's office (the rocket cufflinks and the laser shoes), but neither of them know how to make them work. Meanwhile, the Kasaavin start appearing outside the construction site.
Following the attack on the gallery, the Doctor makes a surprising discovery: the man she met at the gallery and is letting her stay at his house is Charles Babbage, inventor of the difference engine. This means that Ada Gordon is actually Ada Lovelace, the mother of modern computing. The Doctor also notices a strange statuette in Babbage's study, one that looks exactly like one in the Master's TARDIS. Babbage explains that is called the Silver Lady, and that it is capable of moving and projecting images, which are really the Kasaavin. The Doctor quickly explains the Kasaavin have been studying Ada, and the Master has been allowing them to establish a presence on Earth throughout time, hence the multiple Earths in Barton's files. Using the Silver Lady, the Doctor summons a Kasaavin to use her sonic to direct herself back to the 21st century. Unfortunately, Ada grabs her hand at the moment of transport and they disappear.
They reappear in what they learn to be Paris, 1943, as the city is burning in the ravages of WWII. Hearing a patrol, a woman hides the Doctor and Ada under the floor of her apartment. The patrol, led by the Master, blasts the floor with machine gun fire, but the woman remains silent. After they leave, the Doctor deduces that with the hidden radio equipment from the British, the woman must be Noor Inayat Khan, member of the Special Operations Executive and first female radio operator to be parachuted into a war zone. She starts to put together a plan to return to the present.
In the present, Barton takes a moment from hunting Team TARDIS to visit his mother, or rather kidnap her and hold her prisoner in a hangar. According to Barton, she was never impressed by his achievements, and decides to reward her by letting the Kasaavin kill her, claiming that she will be the "first" of whatever it is he wants to do. Meanwhile the Kasaavin move in on the team, forcing Graham to use the laser shoes to fend them off. Yaz calls her sister to tell she's alright, which brings in Barton's men. But Graham uses the laser shoes again to allow them to take their phones and car to go to where Barton was. However, when they get to the hangar, they find only Barton's mother's body, as well as the Silver Lady. Barton calls them to gloat and reveals that he allowed the Kasaavin to experiment to further his plans.
The Doctor, using Noor's radio equipment, begins casting a four-beat signal to attract the Master's attention. She then makes mental contact with him, and they arrange a meeting on the Eiffel Tower. The Master explains that he used a perception filter to hide his true face from the Germans, and that he was responsible for the attacks in the present. The world's intelligence organizations were becoming aware that the Kasaavin were there, and had been for a long time. They had been merely observing Earth and gathering intel, but now the Master has convinced them to attack instead, with Barton's help. Meanwhile, Noor sends a message from the Doctor to the British, and she and Ada find something in the streets of Paris, and send a picture of it to the Doctor.
The Doctor theorizes that Yaz and her being time travellers, plus her being a Time Lord, allowed them to be taken to the Kasaavin's realm and not be killed. The Master brags that his real plan was to capture the Doctor and create chaos, and he'll be able to deal with Barton and Kasaavin after they destroy humanity for him. But the Master has another secret: He managed to find the pocket dimension containing Gallifrey... and found it to have been razed again. But before the Master can complete his revenge, he is interrupted by German soldiers coming up the tower. The Doctor reveals what the message she had Noor send to the British was: telling them what a great source of information the Master has been as a double agent! She deactivates his perception filter and leaves the Master to be captured by the Germans. The Doctor then meets up with Noor and Ada where they took the picture: outside of the Master's TARDIS, still in Outback mode.
With a way back to her home time, the Doctor uses the TARDIS to confirm that the Kasaavin have been monitoring Earth's top technological minds. Namely, every human being instrumental to the development of the computer. And that's when the Doctor realizes part of what is going on. In the present day, Barton is holding his keynote speech in London while Team TARDIS follow via video link from the hangar. He mockingly thanks the audience for allowing his company access to all their information, explaining that since DNA is able to carry so much data, he could convert the large bulk of humanity into lifeless hard drives with him in charge. He activates the Silver Lady, summoning countless Kasaavin and causing everyone's devices to start reformatting them. Graham and Ryan trying to use their spy gear to break the Silver Lady's casing doesn't work, and they are interrupted by the Master (who got there the long way round) as Yaz starts being reformatted.
Suddenly, the reformatting process stops, forcing Barton to retreat and the Master to wonder what went wrong. From the fog, out steps the Doctor, along with Ada and Noor. The Doctor explains that she realized the Silver Lady in Babbage's house was the same that was in Barton's office, and used the Master's own TARDIS to rig it to shut down and banish the Kasaavin back to their dimension for good. As the Kasaavin start returning to the hangar, the Doctor also reveals the Master's planned betrayal by playing a recording of their conversation on the Eiffel Tower. The Kasaavin drag the Master with them to their dimension, leaving the Master to rage against his enemy.
But there are still some loose ends. The Doctor uses the Master's TARDIS to go back in time to set the notes in Barton's plane for Ryan to find, then sets about returning Noor and Ada to their times. But the Doctor also wipes their memories of her and of all the future events they have witnessed. Back in her own TARDIS, the Doctor can't stop thinking about the Master's news of Gallifrey, and rushes to the pocket dimension to see for herself. Sadly, the Master was telling the truth; much like the last day of the Time War, the dome is broken, and the once shining cities of Gallifrey have been reduced to smouldering rubble. The Doctor receives a message from the Master, revealing that, to no one's surprise, he was the one who destroyed Gallifrey out of rage of what he discovered, something so awful, it terrified him: the founding fathers of Galifrey had lied to the Time Lords, and it has something to do with the Timeless Child. Even the mention of it causes the Doctor to experience a painful vision of a child in robes, but the Master cruelly chooses not to reveal anything more to her.
After travelling to a few planets, Graham, Ryan and Yaz ask the Doctor what's wrong, and ask her to tell them more about herself. The Doctor opens up to tell them a little about Gallifrey, the Master, and how she started travelling, but when Yaz asks if they can see Gallifrey, she doesn't reveal its destruction; merely that they'll see it some other time. But as she turns away from her fam, the Doctor's face is not as optimistic as it was before.
- Abusive Offspring: Daniel Barton experimented on his own mother.
- Abusive Parents: Daniel’s mother cared nothing for his achievements. Despite becoming the CEO of a company, all she can muster is a sarcastic "Well done". It’s no wonder he killed her.
- Aesop Amnesia: Played With. The Doctor has completely forgotten about how it's wrong to erase people's memories, even when they beg you not to. In this case; Ada Lovelace. Though Justified here, as this is a particular case where not erasing Ada Lovelace's memories would have made it more risky than usual, since allowing her to retain her memories of 21st century technology would have a significant chance of altering the course of history, as she actually traveled to the future and witnessed the existence of technologies directly related to what she was going to be famous for. The only other historical character allowed to do that in the revived series has been Vincent van Gogh, who saw his own legacy as a painter within a museum, with much more benign consequences. The Doctor could have explained her reasons and let Ada choose to let the Doctor erase those memories, but she never gives her the chance.
- Actually, That's My Assistant: C first assumes Graham is the Doctor, having not gotten word about her latest regeneration.
- Advertised Extra: Stephen Fry as C is killed off after a few scenes.
- Agitated Item Stomping: How Ryan, Graham and Yaz destroy their phones when they get contacted by Barton and realize the tech mogul's framed them and they're now fugitives.
- Ambiguous Situation: Just what point of his/her timeline does this story’s version of the Master occur in?
- Appropriated Appellation: "O" took the Code Name because the head of British intelligence would say, "Oh god!" every time he walked into the room. After The Reveal that he's The Master he enjoys the Doctor's Oh, Crap! response, implying that's really why he chose that name.
- Arc Words: The Timeless Child, having gone unmentioned since its previous reference a season ago, gets brought up again; apparently it's tied to the lie that the founders of Gallifrey told to the Time Lords, and upon which their entire civilization was built.
- Artistic Licence – Biology: The functions of the body that keep a human alive depend on intact DNA and the proteins made from it. If all of a human's DNA were rewritten, the systems keeping them alive would break down and they'd die. After that, decay would set in and all that data would be lost.
- Artistic Licence – History: Ada Lovelace's maiden name is given as "Gordon". A quick check on The Other Wiki reveals that before her marriage, her last name was actually "Byron" after her father. Especially confusing considering Lord Byron shows up later in the same series, and is explicitly noted as being her (future) father.
- Attention Whore: The Master outright admits that his endless murderous schemes are all to get the Doctor's attention.
- Awful Truth: The Master apparently learned one about the origin of the Time Lords that was so awful he destroyed Gallifrey altogether. Now the Doctor has to figure out what that was.
- When Yaz and Ryan are hiding in Barton's office after dark, he asks them to come out because he knows they're there. It quickly transpires that he's actually addressing the glowing beings.
- Yaz, Ryan and Graham question how the Doctor was able to leave the guide and clues on the plane, only for the Doctor to realise she hasn't actually done that yet.
- Batman Gambit: Yaz makes a panicked call to her sister after being branded a criminal, betting that Barton's people will identify and trace the call. Graham is waiting to ambush the security force dispatched to arrest them.
- Beehive Barrier: The forcefield O activates around his cottage to keep the Kasaavin at bay has a distinct hexagonal pattern.
- Bifauxnen: The Doctor sports black tie when she and her companions go to Daniel Barton's vineyard.
- Black-Tie Infiltration: The Doctor and her companions dress to the nines to infiltrate a fancy party at Daniel Barton's San Francisco-area estate; Graham and Ryan in tuxedos, the Doctor in a tuxedo designed after her regular clothes, and Yaz in a pantsuit with a sequined version of the others' tuxedo jackets.
- Blatant Lies:
- Ryan's epically unconvincing litany of alleged medical problems keeping him on constant leave from his warehouse job and covering for his travels with the Doctor.
- As a Rewatch Bonus following the reveal; O claims that he's never done undercover work — he's the self-proclaimed Master of Disguise.
- Bluff the Eavesdropper: The Doctor has Noor Inayat Khan send a message identifying the Master's German-officer identity as a double agent so that the Germans will intercept the message and arrest him.
- Body Horror:
- The spy who was attacked on the plane has had her DNA scrambled to the point of becoming a brain-dead Humanoid Abomination. Judging by the Doctor's description of what's happened to this poor woman, she's probably lucky she's unconscious. We don't see what happened to the other two or O's guards, but they almost certainly suffered the same fate.
- And as a reminder of what the Tissue Compression Eliminator does, it removes the mass from a victim, shrinking them down to the size of an action figure; since a human body is not equipped to be miniature, the process kills them instantly.
- The Bus Came Back: The Master makes a grand and triumphant return, his Joker Immunity stronger than ever. Also, for the first time in modern Who, instead of the laser screwdrivers, disintegrators and sonic umbrellas of the past decade or so, he’s armed with his signature Classic-era weapon: the Tissue Compression Eliminator. For bonus points, the first episode aired a day before the 49th anniversary of the Master's first ever appearance, also using the Tissue Compression Eliminator.
- This isn't the first time the series has riffed on the spy thriller genre. In "The Invasion", the United Nations Intelligence Taskforce was introduced as a plainclothes spy organisation, and the episode had a Corrupt Corporate Executive running a global industry who had converted his body with technology proved by alien invaders he was in league with.
- Yaz's sister Sonya's interest in Ryan is brought up again, as she wants his phone number. Ryan, by now, isn't averse to her getting said number.
- UNIT and Torchwood are mentioned as being "gone" and unable to deal with the alien threat; UNIT having been grounded by funding issues in the previous episode, and Torchwood having been officially disbanded as C implies the events of Children of Earth did that. Notably, this is the first time Torchwood has been mentioned since 2008, let-alone acknowledged within its shared continuity.
- The Master's TARDIS makes its first appearance in a TV story since "The Ultimate Foe", during which it also took on the appearance of a wooden building.
- The Master once used the drumbeat in his head to get the Doctor's attention. Here, the Doctor uses a Morse code signaller to get the Master's attention... by sending 4 short pips in quick succession.
- It's not the first time the Master has teleported off of a stricken airliner.
- The Doctor initiates a telepathic conference between herself and a fellow Time Lord, saying "Contact", a technique we haven't seen since "The Three Doctors". She even refers to it as "classic".
- The artron energy that time travellers pick up from the Time Vortex comes up again: the Doctor and Yaz were teleported to the Kasaavin's dimension instead of being killed because the entities were confused by it.
- At the end of the episode, the Master mentions the Timeless Child.
- Following on from "Resolution", Yaz knows something is really troubling the Doctor because the latter has gone quiet.
- The Master introduces himself as "I'm her best enemy" to the confused companions, the same way the Third Doctor introduces the Master to Sarah Jane in "The Five Doctors".
- Camping a Crapper: The MI6 agent who uses an airplane bathroom as a private spot to check out a secret message is attacked and rendered brain-dead by an alien entity before she can leave.
- Captain Obvious:
- The MI6 agent driving the car containing the Doctor and company points out that the sat-nav "shouldn't be doing that" when it begins glitching.
- Graham states what is happening so often that O asks, "Is he just here for the running commentary?" Graham then needles Ryan about doing the same thing later.
- Celebrity Paradox: Stephen Fry exists in the Whoniverse — he was briefly mentioned by the Twelfth Doctor in "The Husbands of River Song" as one of River Song's past husbands.
- Chase Scene: The Doctor and friends chase Daniel Barton on motorcycles through a vineyard, with Barton leaning out of his car to shoot at them.
- Chewing the Scenery: Once his identity is rumbled, "O" drops all subtlety to his performance.
- Chekhov's Gun:
- The silver humanoid statue first seen in Barton's office. Called the Silver Lady, it's actually a device built by the Master that has been on Earth since the 1830s and is designed to help the Kasaavin enter this dimension.
- The laser shoes and the rocket cufflinks.
- At the invention fair (not-yet)Lovelace and Babbage are attending, grenades for home defence and a Steampunk machine gun are among the gadgetry on display. Ada goes for the weapons while the Master is too occupied with the Doctor to pay attention to her and attacks him with them, forcing him to flee the scene.
- Chronic Backstabbing Disorder: The Master plans to betray the Kasaavin and Barton once they do his dirty work for him. The Kasaavin are not happy with him when the Doctor reveals this to them.
- Cliffhanger: Part 1 ends with the Doctor's companions left behind on a crashing plane while the Doctor is taken to the mysterious realm of the aliens.
- Cliffhanger Copout: Defied: the conflict with the plane crashing is resolved with Ryan discovering some notes from the Doctor hidden on the plane instructing him how to pilot the plane even though the cockpit is gone. Later on in the episode, we see the Doctor go back to when the plane was being constructed in order to leave those notes.
- Come Alone: Oddly enough The Master does meet the Doctor alone at the top of the Eiffel Tower as agreed, though only because he thinks he's won.
- Comically Missing the Point: The Doctor mistakes a game of blackjack for snap.
- Continuity Nod:
- This is not the first time someone's tried to kill the Doctor by remote-controlling the satnav of a vehicle they're in and making it drive somewhere perilous.
- The Doctor refers to her being a woman now as "I've had an upgrade." Missy referred to being a woman as "Some of us can afford the upgrade!"
- When C expresses skepticism about the existence of aliens, the Doctor retorts that he should ask the people at GCHQ.
- The Doctor's evening-dress coat sports a red inner lining, like Twelve's outfit.note The double-breasted style of the coat is visually similar to Eleven's brief period in a green greatcoat, helped by the presence of a bowtie.
- This is not the first time a seemingly ordinary building in the middle of a desert-like region has turned out to be a disguised TARDIS.
- The Master likes it when the Doctor says his name.
- The Doctor disapproves of a character's willingness to use Stuff Blowing Up, but not too much to let it be used to save the day, and we get vague hints that the Doctor is not what he/she seems.
- This isn't the first time a non-white female companion has had her phone calls to their family traced by the Master and his allies, although in this case it's used to the good guys' advantage. In general, Ryan, Graham and Yaz being framed for a crime and forced to go on the run and off-grid is very reminiscent of what happened to the Tenth Doctor, Martha and Captain Jack in "The Sound of Drums", a story that also involved the Master.
- The Thirteenth Doctor is yet again grabbed in a chokehold by a male villain she's just intentionally angered, but isn't concerned about it because she knows things are going her way.
- The Doctor shows up with two historical guest stars and the companions fear they're being replaced.
- The Doctor being reminded to go back in time in order to rig Barton's airplane to save her companions' lives is reminiscent of Eleven's time-hopping in an almost-destroyed universe.
- Ada's protests about getting Laser-Guided Amnesia are reminiscent of what happened to Donna Noble.
- The glowing creature trapped inside a cage is reminiscent of the trapped "ghost" in "Army of Ghosts", and their method of entering this dimension affects time travellers different from regular folk.
- O mentions the unlikelihood that Daniel Barton's identity was faked, since with the extensive files and photographs of him at all stages of life, it's hard to falsify that kind of legend. Yaz chimes in that it isn't impossible, though. Funnily enough, exactly what he did a few regenerations ago as "Harold Saxon".
- Similar to what he did with Bill, the Master spends time befriending the human trio (in particular Graham, who he also tempts with knowledge about the Doctor, and Yaz, who he gets cozy with at the craps table and who he wraps his arms around to hang on during the bike chase) for no real reason except to rub it in to them later when he reveals himself.
- The Doctor gets to indulge in another round of The Tape Knew You Would Say That, this time via foreknowledge of her companions' characters rather than a complete stranger's timey-wimey transcript.
- Graham mentions what the Doctor told him and Grace about regenerating the night they met while the companions are putting the pieces together about the existence of regeneration.
- The Doctor once again tastes the air to get her bearings.The Doctor: I'm getting nineteenth century... early... with a touch of mid... top notes, London... steam? Why am I getting steam?
- The Doctor mentions that the Master never apologized for making a past incarnation of hers fall off Jodrell Bank radio telescope.
- Hakim Khan's Conspiracy Theorist tendencies return, as he (in this case correctly) assumes that the family's temporary paralysis during the thwarted Kasaavin attack was the result of a conspiracy.
- The Doctor's deflection of Yaz's request to visit Gallifrey at the end brings to mind Ten doing the same to Martha early in "Gridlock".
- The Master coming up with a lame pseudonym just to see the Doctor's reaction brings to mind the Delgado Master using such utterly ridiculous aliases as "Emil Keller" (Emil being derived from the Latin aemulus or "rival"), "Professor Thascalos" (Greek for "Master"), "Inspector LeMaitre" in the novel Last of the Gaderene (French for "The Master"), "Reverend Magister" (Latin for...you guessed it), and "Colonel Masters" (he wasn't even trying that time).
- Continuity Snarl: Gallifrey is still in its pocket universe in this episode despite being removed from it prior to the events of “Hell Bent”.
- Conveniently Empty Roads: Justified. The Doctor and Fam on motorcycles pursue the human villain's limousine through dirt roads in the middle of a crop, albeit one that's not far from a large social gathering.
- Corporate Conspiracy: The search engine/data-handling company VOR, headed by Daniel Barton, that's collecting everyone's data for the purpose of turning most of humanity into Wetware CPUs.
- Death in the Clouds: C explains to the Doctor and companions that the woman he's taken them to see, one of his agents, was found unconscious in an airplane bathroom after making prearranged contact with an informant. As the Doctor discovers when looking at the data, the woman has been effectively murdered via her DNA being rewritten and corrupted.
- Department of Redundancy Department: The Doctor's message to O: "Big crisis. Major crisis. Serious crisis. Big serious crisis."
- Desolation Shot: What the Doctor sees when she arrives on Gallifrey.
- Disapproving Look: The Doctor and Ada Lovelace exchange one when Charles Babbage says of the Silver Lady that "like all great ladies, she is as much for decoration as for purpose."
- Disproportionate Retribution: In response to the lie he uncovered, the Master has apparently laid waste to the entire planet of Gallifrey, not just those in charge but every civilian as well, including the current generation of all the children the Doctor counted on that dark night mentioned in "The Day of the Doctor".
- Doesn't Like Guns: The Doctor tells Ada that she doesn't approve of her firing the ball-bearing machine gun, even when it's being aimed at the Master and Ada's using it to save the Doctor and a room full of bystanders. She approves when Nora Khan says she doesn't have a gun—despite being an SOE agent in Nazi-occupied France—due to her pacifist beliefs.
- Double Agent:
- C tells the Doctor that Barton is suspected of having become one. It turns out he now works for/with the Master.
- The Doctor gets the Master's Nazi officer disguise framed for being a double agent by having Noor Inayat Khan send a radio message she wants intercepted claiming that he's been a valuable source of information.
- Dramatic Irony: Thirteen is a lot more pissed at the Master than her Tenth and Twelfth incarnations, and why shouldn't she be? She doesn't know that Missy tried to stand with her, only to get killed on the way.
- Eat the Evidence: The MI6 agent on the airplane eats the paper with the secret message she's been passed after photographing it, just before she's attacked.
- Eiffel Tower Effect: In Paris, the Eiffel Tower is clearly visible from Noor's window, and the Doctor later meets the Master at the top of the tower. Curiously enough, Ada does not comment on it, as the tower did not exist in her time (then again her view of a city undergoing an air raid was somewhat distracting).
- Eldritch Abomination: The Kasaavin. When one is interrogated by the Doctor about where it's from, the only response she gets is "far beyond... your understanding."
- Eldritch Location: The home dimension of the Kasaavin is an endless forest of cables and mist that, judging by the Doctor's run-in with Ada, is also a Place Beyond Time. And the only way to enter or exit is for the Kasaavin to give you passage.
- Elevator Escape: After revealing that she's just gotten his disguise implicated as a Double Agent, the Doctor exits her meeting with the Master on the Eiffel Tower via the lift. He's left banging on the door in a rage before being held at gunpoint by several Nazis.
- Engineered Public Confession: The Doctor secretly records the Master boasting that the Kasaavin are nothing but pawns to him and will be cast aside once they've outlived their usefulness. She then plays this recording to the Kasaavin, who respond by turning on the Master.
- Even Bad Men Love Their Mamas: Subverted hard. Daniel Barton feels no love for his mother, experimenting on her and planning to have her wiped out with the rest of humanity.
- Even Evil Has Standards: Whatever it was that the Master discovered about the origin of the Time Lords and the Timeless Child, he laid waste to Gallifrey to punish them for it. It is implied from the Doctor's lack of reaction that he may have been right to do so — and they weren't exactly saints before this revelation, either.
- Exact Words: O tells the Doctor she should look out for the "spymaster" behind whatever's going on. As he points out during The Reveal: "Or should I say... the spy-Master?"
- Facial Dialogue: When the Doctor catches on to the fact that "O"'s story doesn't quite add up, there is brief close-up on the Master's face, during which he is clearly considering whether he should try to keep the whole O facade going and come up with a quick lie to belay the Doctor's doubts for just a little while longer, or just straight up give the game away which will allow him to fully indulge in some Evil Gloating. It is also clear which one of the options he finds to be the most appealing.
- Fiction 500: Daniel Barton is the CEO of VOR, a company which seems to be the Whoniverse equivalent of Google: started out as a search engine which quickly became the most popular in the world, has since expanded into a ton of different areas of research, but has recently been accused of some shady business practices.
- Foreshadowing: O being The Master undercover is hinted at repeatedly:
- The lasers used to kill the driver and C are distinctly orange, resembling the beam from Saxon's laser screwdriver.
- When the Doctor first mentions "Horizon Watcher", she says he's an old friend but then backs down a bit and says he might be a friend because she's only met him once in person.
- C's last words — he suggests that Barton may be a double or triple agent for someone, and is shot after being asked who he might be an agent for. His surprised reaction? "Oh."
- When the Doctor realises they're in a spy thriller she tells the fam that they shouldn't trust anyone. Then she trusts O. Of course that's going to be a mistake.
- When O introduces himself, he claims he took the codename because C used to react with an "Oh, god" whenever he came into his office. It turns out that that exact reaction of surprise or fear is precisely why he took that identity.
- O's technology, which he explains having as being Properly Paranoid, manages to hold off the glowing creatures when one nearly got through the TARDIS's doors and the Doctor herself hasn't been able to get a reading off them.
- O mentions how unlikely it would be for Barton's identity to be fake given how many pictures there are of him at various ages on the Internet. The Master had done this before as Harold Saxon (here he does a Kill and Replace on the real O, making use of his identity; whereas for Harold Saxon he'd photoshopped a bunch of pictures and manipulated the public into electing him as Prime Minister).
- The alien data stolen from Barton's computer is encrypted using the same technique that O used on the picture he sent to the Doctor.
- O offers Graham information on the Doctor in a fashion implying that he may be trying to erode his trust in her.
- Later, he tells the Doctor she should be looking for the "spymaster" behind the conspiracy.
- There is a shot of a house outside the aeroplane that brings to mind The Wizard of Oz. Guess who used to call themselves the Wicked Witch?
- A Form You Are Comfortable With: Inverted. The glowing creatures have humanoid forms, but claim that they've taken that form to mock humanity.
- Barton, upon realizing that Ryan, Graham and Yaz are alive and got to the UK on his damaged plane, uses his resources to frame them for bombing the plane and makes them fugitives.
- The Doctor gets the Master out of her way in wartime Paris by implicating the German officer he's impersonating as a double agent, leaving him held at gunpoint as she escapes in the elevator to steal his TARDIS.
- Gender Vocabulary Slip: The Doctor presents herself as the Marvellous Apparating Man. Lady! Apparating Lady!
- Goggles Do Something Unusual: The MI6 agent on the airplane is wearing glasses with a built-in camera, which she uses to photograph a secret message before she is attacked.
- Go Mad from the Revelation: Something that the Master has discovered about Time Lords and The Timeless Child had him so ticked off that he destroyed the cities of Gallifrey!
- Good is Not Nice: The Doctor points out the Master's new look isn't exactly the Aryan ideal and removes the perception filter before stealing his TARDIS, leaving him both with angry Nazis and on The Slow Path.
- Googling the New Acquaintance: Daniel Barton looks up "Sofia Afzal" and "Logan Jackson" on his smartphone to determine they are who they say they are. Thanks to tech from MI6, Yaz and Ryan's cover identities do possess a real online presence so Barton doesn't find anything amiss. Called back to later, as Barton sarcastically asks Ryan if he should call him Logan as he makes the team fugitives.
- Happy Ending Override: The Master kills off all the Gallifreyans the Doctor went to such trouble to save in "The Day of the Doctor".
- Head Desk: The Master smacks his forehead against the console of his TARDIS several times upon detecting that the Doctor is somehow still alive and has just travelled in time.
- Heroic BSoD: Illustrated literally blue; as the Doctor sits staring into space after discovering the fate of Gallifrey, all the normally orange crystals in the TARDIS have turned blue. It also seems to persist, as the Doctor barely says a word during the next five planets she visits with the Fam.
- His Name Is...: C is about to reveal who he believes Barton is working for when the Master snipes him with a laser rifle.
- Historical Domain Character: Noor Inayat Khan, Charles Babbage and Ada Lovelace.
- History Repeats:
- Sorta; once again, the Master steals a body. This time though, it's via Kill and Replace.
- The Master's Evil Plan is right out of the Pertwee years—a plan to destroy humanity purely to spite the Doctor, with a human ally and a race of alien invaders who end up turning against the Master. It even sees the return of the Tissue Compression Eliminator.
- Gallifrey and the Time Lords have been killed off. Again.
- How Did You Know? I Didn't: O's explanation for how his surveillance tech manages to hold off the glowing creatures. It turns out later that this is a lie.
- Humanoid Aliens: The enemies take humanoid forms to mock humans.
- Hypocrite: The Doctor calls the Master out on using Nazis to find her as being a rotten thing to do (which it most certainly is)... only to do the same thing to him. May count as Laser-Guided Karma.
- Hypocritical Humor: During the Black-Tie Infiltration of Barton's birthday party, the Doctor tells everyone to blend in. Gilligan Cut to everyone making it blatantly obvious they've never gambled before. The Doctor then one-up's this by telling Barton's she's onto his Evil Plan.
- I Can't Sense Their Presence: The glowing aliens can be observed, but even the Doctor's sonic screwdriver can't detect their physical presence.
- In the Past, Everyone Will Be Famous: Justified with Charles Babbage and Ada Lovelace who are connected to the aliens plans; less so with Nora Khan.
- Idiot Ball:
- Yaz and Ryan forget to use their camera-jamming device on the cameras in Barton's office, and end up on the security footage he later watches. Or, if the device has to be aimed at a camera and this one was hidden, then the ball goes to whoever designed the device without including a way to locate hidden cameras.
- The Master doesn't bother to disguise his TARDIS in 1943 Paris, so Noor has no trouble noticing that it's out of place. The Doctor chalks this up to the Master being so arrogant that he didn't think anybody would notice anyway.
- Lampshaded In-Universe when the companions forget to read the manuals on their spy gadgets and Ryan does some gloating to Barton's minions on their intentions...which they proceed to notify him of.
- Imposter Forgot One Detail: The Master manages to fool the Doctor into thinking he's O throughout the entire first episode, until he makes a throwaway comment about never having been good at sprinting."O": I was the last one in every race at school.
The Doctor: Nonono, I read your file. You're a champion sprinter.
"O": Hm... Got me.
- I Need a Freaking Drink: Charles Babbage is last seen taking a very large swig from his glass after the Doctor and Ada are disappeared by a Kasaavin.
- Intangibility: The glowing creatures can phase through walls, often having the appearance of the wall they've passed through afterwards.
- Internal Reveal:
- The Doctor finally tells her companions what her species is called and where she's from.
- It's also revealed to them that she hadn't been joking about having previous bodies and being male.
- Ironic Echo:
- The Master called himself "O" in anticipation of the Doctor's Oh, Crap! reaction to him. When she outwits him, he gets an "Oh..." of his own.
- A visual one occurs shortly after he's trapped in the Kasaavin dimension: the camera pulling back to show him totally alone directly mirrors the Doctor's entrapment in the previous episode's cliffhanger.
- Karma Houdini: Barton is last seen calling for an extraction team, implying he escapes the doubtless angry audience and any other pursuit.
- Kick The Son Of A Bitch: The Master destroys Gallifrey after learning the Awful Truth. Considering what they did to him and the Doctor on multiple occasions (not to mention the many, many atrocities committed during the Time War), it's not entirely undeserved...
- Kill and Replace: The fate of the real "O", courtesy of a Tissue Compression Eliminator.
- Kneel Before Zod: In 1834, the Master demands the Doctor kneel before him if she wants him to stop killing more people. Since there are innocent lives at stake, she complies. Then immediately subverted in a way that perfectly encapsulates their relationship, when he promptly kneels down himself to have an intimate conversation with her.
- Laser-Guided Amnesia: The Doctor brainwipes her temporary companions Noor and Ada when returning them to their original places in time and space so as to not adversely affect future history.
- Leaning on the Fourth Wall: Yaz's dad tries to get Alexa to play "Rubber Soul", only for it to keep mishearing his request. Almost as if they couldn't actually get the rights for the album...
- Literal Metaphor: Upon revealing himself, the Master mockingly says that the real "O" is "A man very close to my heart." Then he shows how literally he means it by producing a small matchbox... containing the real "O", miniaturized by the Tissue Compression Eliminator
- Meaningful Name: O. As in the reaction.
- Meanwhile, in the Future…: Part 2 flips between the Doctor's conflict with the Master in two different past time periods and the companions' efforts to try and derail Barton's plans in the present day. To make things more fun, the amount of time everyone experiences is indicated to be different: the Doctor (and her allies Ada and Noor) experience at most a few hours; Ryan, Graham and Yaz go through around a day or more, due to having been initially stuck on a plane flying from San Francisco to the UK and later being seen taking shelter at night; while the Master's initial hunt for the Doctor in two different time periods is indicated by the growth of a Beard of Evil to take longer than is shown onscreen, even before he gets stuck on The Slow Path.
- Mega-Corp: VOR is described as having more power than most of Earth's nations, thanks to the enormous volume of work it's subcontracted to do by various government bodies.
- Mirror Character: Even if Time Lords are above race and gender, the Master and Doctor still use them to degrade the other; the Master making the female-looking Doctor kneel in front of him, and the Doctor forcibly dropping the perception filter to alert Nazis to the fact that the Master looks like a MOC.
- Mirrors Reflect Everything: The Doctor uses the SUV's rear view mirror to deflect back the laser that killed the driver and destroy the computer, stopping the hijacking.
- Multi-Part Episode: Only the second two-parter of the new series, after "The End of Time", to use the "[Title], Part X" style of title. Fittingly, both stories aired in part on New Year's Day (and feature the Master). "The End of Time, Part 2" also aired exactly 10 years before "Spyfall, Part 1", forming a bookend of sorts, with the Master exiting the show in the former and re-entering in the latter (although the character obviously appeared in the intervening years as Missy). Both of the second parts of those episodes also involve the destruction of Gallifrey.
- Murder by Remote Control Vehicle: The SUV the Doctor and her companions ride in when they're being escorted to MI6 is hijacked remotely, the driver is disintegrated, and our heroes are nearly driven in reverse over a cliff before the Doctor rips off the rear view mirror to deflect the laser and stop the vehicle.
- Mythology Gag:
- The old fan joke about watching Doctor Who from behind the sofa comes to life within the show when Ryan and Yaz witness Barton's rendezvous with the aliens from behind a sofa in his office.
- The Doctor says she spent 123 years in the Outback once and saw a lot of great rocks, which may be a nod to the classic series using abandoned quarries for so many alien planets (which got a nod at the time with Tom Baker arriving on a new world and exclaiming enthusiastically, "Oh look, rocks!").
- O tells Graham that there are "inconsistencies" in his collected information on the Doctor, a nod to the series' perpetually contradictory continuity.
- The Master takes The Slow Path, like he did in The Curse of Fatal Death. He doesn't spend it in a sewer, though.
- The Name Is Bond, James Bond: The Doctor introduces herself at the vineyard thusly:The Doctor: The name's Doctor. The Doctor.
- New Era Speech: Barton's speech at his alleged "new tech rollout" is clearly intended as one, but things don't go as planned thanks to the Doctor foiling the plot.
- New Media Are Evil: Barton makes it clear in his speech that his Evil Plan is only possible because of how willing people are to share every facet of their lives on social media.
- No Equal-Opportunity Time Travel: One of the likely reasons for why the Master's 77 years on The Slow Path were so infuriating, since he doesn't look white anymore.
- No One Could Survive That!: You'd think The Master would have stopped being surprised at the Doctor and his companions escaping his inescapable deathtraps.
- Noodle Incident:
- The Doctor has the TARDIS in a car mechanic garage at the start of the episode, allegedly draining water out of slides, lakes and a rainforest that are apparently somewhere inside.
- The Doctor claims to have spent 123 years living in the Outback, and saw some "great rocks".
- The Doctor and her companions know how to ride motorbikes because of a visit to the "Great Calespan Bike-Off".
- When theorising that the realm of the Kasaavin might be inside a larger creature, the Doctor hopes she isn't inside a liver, having apparently been in one multiple times.The Doctor: People always get so offended. "What are you doing in my liver again?"
- The Master has had a very frustrating seventy-seven years marooned on Earth. The places he's escaped from...
- Oh, Crap!:
- The Doctor, when one of the creatures proves capable of breaching the TARDIS's locked doors.
- Yaz and Ryan when they think they've been discovered hiding in Barton's office. Then they get it again after Barton's gone when Yaz is attacked and vanished by one of the creatures.
- The Doctor again, when she finally realizes what "O" is insinuating: namely, he's her Arch-Enemy the Master. The Master states that the trope itself is precisely why he chose to have "O" as his code name to begin with.
- The Doctor again, when she finds that Barton has vanished from his plane, with a bomb the Master has deadlock-sealed so she can't shut it off left there instead. This leads to the cliffhanger where the Doctor has been vanished to the same nowhere-place Yaz was in, while the companions are left on a crashing, cockpit-less plane.
- The Master when his plan comes undone. He has the exact same reaction the Doctor had to his identity.
- Omnicidal Maniac:
- Barton is willing to turn humanity (except for a few collaborators) into a database for alien invaders just because.
- The Master as usual; not only willing to destroy humanity For the Evulz but his own home planet as well.
- One-Letter Name: The chief of MI6 known as "C" (as they are in Real Life), along with "O."
- One-Steve Limit: The guest actors for Part 2 include Kenneth Jay as "Perkins", who is presumably a different person than Frank Skinner's character from "Mummy on the Orient Express".
- One-Word Title: "Spyfall".
- O.O.C. Is Serious Business:
- The usually perky Yaz is visibly shaken on her return after being trapped in the realm of the Kasaavin.
- The Doctor is normally very talkative, even when she's by herself, as shown by the first scene of part 2 when she's busy chattering to herself while in the dimension of the Kasaavin. After she takes the TARDIS to Gallifrey and sees that the Master was not lying when he said it was completely destroyed, she is silent while listening to the Master's geolocked message and continues to say nothing while angrily throwing the message away and then while sitting with her back against one of the pillars in the TARDIS. She evidently continues to be less-than-chatty while travelling with the fam, as Graham notes towards the end of the episode that she has barely said a word during their trips to five different planets. Naturally she denies that there's anything wrong.
- Speaking of the Master's message: this incarnation of the Master is, when not posing as someone else, a Psychopathic Manchild with a Hair-Trigger Temper who is constantly flipping between apparent calm and rage. His demeanour in the message he leaves for the Doctor is, in sharp contrast to this, completely serious, and he even seems somewhat shaken by what he's talking about. He only slips partially back into his usual demeanour at the end when he says that he's not going to tell the Doctor what Awful Truth he discovered because that would be "making it easy" for her.
- Out-of-Genre Experience: Doctor Who does Tuxedo and Martini Spy Fiction.
- Overly Pre-Prepared Gag: The Master contrives to get his civilian identity known only by the letter O, just so the Doctor's surprised “Ooooh!” when she figures it out will sound funny.
- Perception Filter: The Master uses one when posing as a Nazi officer in 1943 because his current incarnation can't pass for "the Aryan ideal" otherwise.note The Doctor's plan to get him out of her way involves forcibly dropping it.
- Place Beyond Time: It's implied that the Kasaavin's dimension is somewhat this, with the Doctor arriving there from 2020 and meeting Ada Gordon-later-Lovelace visiting from 1834 just minutes later.
- Professor Guinea Pig: Yaz's scan of Barton confirms that he has only 93% human DNA. He eventually explains that the Kasaavin technology can convert human DNA into one of the most efficient data storage tools on Earth, and he's a "proof-of-concept".
- Psychopathic Manchild: The Master in this iteration, when the Doctor finally catches on to who he is, starts skipping around the plane and clapping like a delighted toddler.
- Rags to Riches: While posing as a reporter interviewing Daniel Barton, Yaz notes that he went from a poor British kid who grew up on a council estate to a multi-billionaire who owns a fleet of private aircraft.
- Replacement Goldfish: Discussed; because she was separated from the others for a good while, and showed up with Ada and Noor to confront the Master, the Doctor is (briefly) accused by her companions of replacing them. The Doctor wastes no time in resolving the confusion.
- The Reveal:
- O is actually the Master, who killed the original and took his identity before he even started the job.
- The Master discovered something about the foundation of Time Lord society that was so horrifying, so utterly appalling even for him, that he found a way to the pocket dimension containing Gallifrey... and razed it, once again rendering him and the Doctor as potentially the last two Time Lords in existence (depending on whether any other Time Lords were away from Gallifrey at the time).
- Rewatch Bonus:
- Many things, especially the sequence where O's security is able to hold off the Kasaavin, make a lot more sense with the knowledge that O has been the Master all along.
- It's actually acknowledged in the second part's Previously On segment: it's edited so that C's mentioning O for the first time is immediately followed with him getting shot and remarking "Oh".
- Applies again on another level after the reveals of part 2.
- Rule #1: The Doctor tells her companions that the first rule of espionage is "Trust no-one." Given that the Doctor is a natural rulebreaker, it's not surprising she forgets the rule and gets in trouble. The trope is amusingly lampshaded later on.Yaz: Ryan, you're panicking. Rule 1—no panicking.Ryan: I thought Rule 1 was don't trust anybody?Yaz: Rule 1a, then. No panicking while you're not trusting anyone.
- Running Gag: The gag from early Series 11 about the Doctor occasionally forgetting her new gender returns when she loudly announces herself to the crowd at the Alexandria Gallery as "THE MARVELLOUS APPARATING MAN!" ...no, sorry, "THE MARVELLOUS APPARATING LADY!"The Doctor: [frustrated] Every time!
- Say My Name:
- At the invention fair, after she kneels, the Master makes the Doctor say his name several times while holding everyone hostage.
- The Master is last seen in-person stuck in the Kasaavin's dimension, angrily screaming the Doctor's name.
- Scenery Gorn: The shot of Gallifrey, ruined and in flames.
- Self-Made Orphan: Barton willingly hands his own mother over to the Kasaavin, who subject her to lethal DNA conversion.
- Series Continuity Error: Gallifrey is still in its pocket universe in this episode despite being removed from it prior to the events of "Hell Bent".
- Shoe Phone:
- The MI6 agent on the plane is wearing a pair of glasses with a concealed camera.
- C shows Ryan and Graham a pair of shoes with a built-in laser gun, which come in handy in part 2.
- Downplayed, since they're not hiding in really unlikely objects. Yaz's recording device and Ryan's camera when they're posing as reporters both contain secondary functions to scan Barton and his DNA, as well as copy his ID card.
- Upon being given the cover name "Logan", Ryan worries that he doesn't look like Hugh Jackman.
- The title riffs on the James Bond movie Skyfall, while the Doctor introduces herself as "Doctor, The Doctor", and a Bond-esque rendition of her leitmotif from "Resolution" plays during the car chase.
- The Noodle Incident where Team TARDIS learned to ride motorbikes was called the Great Calespan Bike-Off.
- The Master describes his TARDIS, disguised as a house, flying alongside the plane as "a bit Wicked Witch of the West".
- The Master now carries his miniaturised victim around with him, like his parody Doctor Klench in Nebulous.
- The "use the whole human race as computer hardware" plot was reportedly the original plan for what the Machines would be using humanity for in The Matrix, but Executive Meddling at the time thought that it would be too hard to explain to the mainstream audience.
- The Master sums up his plan as "Maximum Carnage", before acknowledging that the Doctor wasn't going to get it.
- O has a complete set of Fortean Times in mint condition. Well he would, given that he's a time traveler who, along with the Doctor, probably caused half the things they write about.
- Shrink Ray: The Master's Tissue Compression Eliminator from the classic series makes its new series debut.
- Sir Not-Appearing-in-This-Trailer: Likely to avoid spoilers regarding his identity, O/The Master was mostlynote absent in promo materials released prior to the premiere. Scenes from this episode featured in the trailers have actually had him digitally removed from them. Also, Sacha Dhawan was not mentioned in the Radio Times cast lists for either episode, even as "O".
- The Slow Path: The Master spent most of the 20th century in hiding after the Doctor stole his TARDIS and stranded him in wartime Paris, forcing him to wait for the day when the plan comes to fruition.The Master: So, I've just had the most infuriating 77 years of my life.
- Space Whale Aesop: It's a bad idea to let tech companies have your credit card details and your mother's maiden name, because with this information they can allow extradimensional aliens to rewrite your DNA.
- Spotting the Thread: The Doctor starts to realize that O isn't who he seems to be because he says he's terrible at sprinting, when O's file, which she's read, says he's a champion sprinter.
- Stable Time Loop: After unravelling the Master's plan, the Doctor is asked how she left instructions for Ryan on how to pilot Barton's plane without a cockpit. This clues the Doctor in on one last thing she needs to do, promptly time-travelling back to the construction of the plane so she can secretly plant said instructions.
- Story Arc: The ending reveals that the Doctor has to figure out what the Awful Truth about the Time Lords was that drove the Master to lay waste to Gallifrey. It has something to do with the Timeless Child mentioned in "The Ghost Monument" — and if she figures it out, maybe she can Set Right What Once Went Wrong.
- Suddenly Shouting: The Master briefly breaks into this in a mixture of satisfaction and irritation when the Doctor attempts to sonic the bomb he's set.The Master: Did you really think I wouldn't make that sonic-proof, Doctor?! Come on!!
- Surprisingly Realistic Outcome:
- As companions with the Doctor for long stretches of time, Yaz and Ryan have a lot of explaining to do to friends and employers about their repeated absences. Graham, who's retired, has less explaining to do.
- Yaz's supervisor lets her know that she is still a probationary officer and needs to finish her probie time or she'll lose her job.
- The Master joins the Nazi party and the audience is lead to believe they joined against a common enemy or because the Master had something they needed. It's only when the Doctor and the Master talk to each other that the audience learns the Master is using a perception filter to work with the Nazis, as the ethnicity of his current regeneration (an Englishman with Indian heritage) goes against the Nazi regime/ideology. When the Master's perception filter is switched off he is arrested and presumably sent to be tortured or become a prisoner. When the Master reappears to Ryan, Yaz and Graham in the present day he's furious and exhausted, implied to be because of the amount of racial prejudice he had to endure and the number of prison escapes he had to do.
- When Ryan asks how the Doctor was able to leave instructions for Graham, Ryan and Yaz on how to land a plane, she quickly realizes she needs to go back in time again so she can leave instructions for her companions on how to land the plane and do it without being noticed by either the Master or Barton.
- Surveillance as the Plot Demands: Barton is able to track down the Doctor's companions through their phones, data mining, and having "cameras everywhere."
- Talking to Themself: The Doctor explicitly takes part in this at the start of part 2 both to assure herself she's still alive, and presumably to calm herself due to arriving in the nowhere-place.
- The Tape Knew You Would Say That:
Graham: I'm not panicking!
- The video instructions the Doctor leaves for Ryan on how to fly the plane include her leaving gaps for them to express surprise, telling them to stop talking back since it's a recording and she can't hear them, and correctly predicting that Graham would be panicking.
The Doctor's recording: Yes you were, and I did just say don't talk back to the screens.
- The holomessage the Master leaves for the Doctor at the end has him predicting some of her reactions to what he has to say.
- Teaser-Only Character: The three spies (the sniper, the airplane passenger, and the guy waiting for an extraction) in the teaser who are all attacked by the mysterious creatures. The passenger is seen later in a medical suite at MI6 headquarters to provide a demonstration of what was done to them.
- Television Geography: The opening scene in the Ivory Coast shows several stiff-leaved upright plants. These are aloes, a succulent species found in arid areas of southern Africa, and nowhere near Côte d'Ivoire in western Africa. Understandable, as this scene was filmed in South Africa, which has lots of different species of aloes.
- This Cannot Be!: After the Master reveals himself:The Doctor: No... no, you can't be.
The Master: Oh, but I can be, and very much am.
- This Is No Time for Knitting: After the Doctor sends Horizon Watcher a message, she gets back a picture of a fish, which the companions and C find inexplicable, and the Doctor is inordinately interested in it even as she and her companions have to flee from the glowing creatures after C's murder. The picture contains an encoded message with Horizon Watcher's location.
- Those Wacky Nazis: While tracking the Doctor to Paris in 1943, the Master uses a perception filter to disguise himself as a Nazi officer and gain command of a unit of spy-hunters. The Doctor considers working with the Nazis to be a new low, even for him.
- Time-Travellers Are Spies:
- Quite literally — Team TARDIS is called in to help MI6 with an alien situation, and Yaz and Ryan even go undercover as reporters. The Doctor and company aren't usually spies, but this time they sort of are.
- The Doctor deduces that the Kasaavin are literally "spies throughout human history" after figuring out what the multiple Earth maps mean.
- Took a Level in Jerkass: Regardless of what Missy thought about putting an end to their endless feud, this incarnation has gone right back to how he was before, fully prepared to destroy humanity and cause chaos just to spite the Doctor. Of course, we don't know if this reincarnation comes after Missy or before.
- Tricked-Out Shoes: C shows Ryan and Graham a pair of shoes with built-in laser guns. Graham takes and wears them, and they come in handy in part 2.
- Unexplained Recovery: It wouldn't be ol' Koschei without this; the easy assumption is that despite being hit with something that's supposed to kill a Time Lord permanently, Missy somehow regenerated and managed to find a way off the colony ship; thinking the Doctor deliberately abandoned them to die, the Master decided Then Let Me Be Evil. Thing is, as you'd expect, there are enough ambiguous details to suggest it's not that simple.
- Unsettling Gender-Reveal: Graham is surprised to learn the Doctor's references to body regeneration and having once been a man weren't in jest.
- Unspoken Plan Guarantee: The Doctor's plan to entrap the Master, steal his TARDIS and leave him stranded in 1943 so she can get back to the present is unexplained until it kicks off.
- Villain: Exit, Stage Left:
- The Master teleports off the plane just before some of the entities send the Doctor into the alien dimension, leaving Ryan, Graham and Yaz stranded on an out-of-control aircraft that is now missing its cockpit thanks to the Master's bomb.
- The last we see of Barton, he's leaving a theatre auditorium and demanding an extraction team as he realises his plan didn't work.
- Violence Really Is the Answer: The Master is holding the Doctor and a room of innocent people at TCE-point. The answer? Ada shoots him in the shoulder with a machine gun, and follows that up with the threat of grenades.
- "Well Done, Son" Guy: Barton has a very strained relationship with his mother. At one point he asks her if being one of the most powerful people on the planet is enough of an achievement to get a "Well done" out of her, and gets a very sarcastic one in return. It's implied that Barton's mother cares less about his success and more about a lack of meaningful communication from him; the most effort he's put into their relationship was sending her a friend request on Facebook (even though he hates using Facebook).
- Wetware CPU: Barton's plan is to convert almost the entire human race into DNA hard-drives using the Kasaavin technology.
- Wham Episode: The Master is back. And it turns out that he's laid waste to Gallifrey (likely leaving him and the Doctor as the Last of Their Kind again) because of some enormous lie he discovered about the history of the Time Lords, something connected to the Timeless Child.
- Wham Line:
- The reveal of O's true identity.
- The Master's hologram message revealing who it was that destroyed Gallifrey, and why.Hologram: If you're seeing this, you've been to Gallifrey. When I said someone did that, obviously I meant– I did. I had to make them pay for what I discovered. They lied to us. The founding fathers of Gallifrey — everything we were told was a lie. We are not who we think. You or I. The whole existence of our species — built on the lie of the Timeless Child. Do you see it? It's buried deep in all our memories. In our identity. I'd tell you more, but... but why would I make it easy for you? It wasn't for me.
- Wham Shot:
- "O" revealing the body of the real O... in a matchbox, having been hit with a TCE.
- The Doctor discovering that the Master had not been lying about Gallifrey being destroyed.
- What Happened to the Mouse?:
- What did the Doctor do with the Master's TARDIS once she got back to the present day?
- It's not entirely made clear if Barton framing Yaz, Graham and Ryan as being plane hijackers is fully resolved, or how it was done if it was.
- No proper explanation is ever really put forth as to what the mysterious plane the Doctor and Ada are stranded on actually is.
- What Would X Do?: Naturally the companions ask what the Doctor would do.
- Where I Was Born and Razed: The Master was born on Gallifrey, and claims credit for its latest destruction.
- Worst. Whatever. Ever!: Graham refers to being picked up by MI6 unwillingly as the "Worst Uber ever!"