It's Christmas Day, 5343, on the human colony Mendorax Dellora. A man walks up to the TARDIS and knocks on the door, despite the sign warning away any carolers. The Doctor, when he opens the door, turns out to have been unwittingly given holographic antlers. Nardole, the man who knocked on the door, is a bit confused about that. He's come looking for the surgeon — there's a medical emergency. So the Doctor agrees to come see what the emergency is. After they leave, a man walks into the street, asking if someone called for a surgeon.
There's a spaceship crashed outside of town. When the Doctor and Nardole arrive, a woman in a long, red hooded cloak comes down the ramp to greet them. She's the one who called for a surgeon. She's also Professor River Song, and her husband is dying. The Doctor is understandably surprised by this news. River is not pleased that the surgeon she hired knows who she is and addresses her by name — she's trying to keep her identity secret — and threatens to remove the organs of the next person who calls her by name. In alphabetical order. The Doctor wants to know which alphabet.
River's dying husband turns out to be the tyrannical King Hydroflax. He has bodyguards with genetically-engineered anger problems, and is practically worshipped by his billions of terrified subjects, who are watching to see the results of the surgery. Hydroflax has the universe's most valuable diamond lodged in his brain. It got stuck there while he was leading a raid. River turns out to have married him because she wants to steal it. She's even arranged a buyer. The surgeon she hired, who was in on the plot, was supposed to remove the diamond, that's all. River would rather Hydroflax didn't survive this. The Doctor is rather disturbed by this plan, and also surprised River hasn't realized who he is yet.
It's at this point in the conversation that Hydroflax angrily intrudes, and reveals himself to be a head attached to a robot body. River and the Doctor wind up taking the head hostage and teleporting away, leaving the robot body with a terrified Nardole to interrogate. River and the Doctor land in the forest, and River's not too pleased at the Doctor's amusement about the fact that they're being threatened by a head in a bag. Shortly, River's other accomplice, Ramone, turns up. River married him, too, and then wiped his memory of the marriage because he was "getting annoying". Ramone tells River that there's no sign of "Damsel" in town. The Doctor is rather taken aback to discover that's River's code name for him.
The Doctor and River head for the TARDIS, parked in town. Hydroflax's robot body follows in pursuit, having taken Nardole's head hostage. At the TARDIS, River reveals she's "borrowed" the TARDIS without the Doctor's knowledge on many previous occasions, to his surprise. She also gives him the most unnecessary forewarning in the history of the show about the discrepancy between the inside and outside of the ship. The Doctor takes advantage of this, and River's continuing ignorance of his identity, to give the hammiest ever "reaction" to the TARDIS' interior. He thinks that's how everyone ought to react. It also transpires that River has a liquor cabinet behind a roundelle in the console room he didn't know about.note
The TARDIS can't take off with only Hydroflax's head on board. The rest of his body's caught up, however, and the Doctor tricks it into getting on board. The TARDIS takes off for River's destination, the interstellar cruise liner Harmony and Redemption, where she's planning to meet the buyer for the diamond. The ship is a haven for the wealthiest murderers around, where genocide comes to kick back and relax. Even the staff are required to have a history of indiscriminate slaughter.
River's buyers aren't after what she thinks they are. So how will the Doctor and River escape the ship? And when will she finally realize who the Doctor is?
This episode has several elements of note:
- It is effectively the coda to the Twelfth Doctor's character arc in Series 9, airing less than three weeks after "Hell Bent" did.
- It is the debut story for Nardole, who by the time of the next episode "The Return of Doctor Mysterio" has become a companion to the Twelfth Doctor (his first since Clara Oswald, not counting various Expanded Universe characters).
- It also introduces as secondary antagonists the Shoal of the Winter Harmony, who go on to be the villains of "The Return of Doctor Mysterio".
- Perhaps most importantly, it brings the story of River Song full circle, depicting the circumstances of her and the Doctor's last night together before his tenth self met her in a certain Library.
- The aftermath of this episode is hugely important to the Backstory of Series 10.
- 10-Minute Retirement: Just like his last post-companion period, the Doctor is in solitary mourning only to be yanked back into action.note
- Actually Pretty Funny: River eventually agrees that Hydroflax's head ranting within the bag is a pretty funny sight.
- Affably Evil: Flemming, the maître d'. He is continually polite to River, though as she says even the staff aboard the Harmony and Redemption are required to have a history of indiscriminate killing.
- A.I. Is a Crapshoot: Hydroflax's robot body destroys Hydroflax's head (and thus kills Hydroflax) once it determines that the head is irreparably damaged. The body proceeds to claim Hydroflax's throne for itself.
- Always Night: Played with. We hear that the nights on Darillium are 24 years long.
- Anguished Declaration of Love: River admits that she loves the Doctor but she honestly doesn't believe that he loves her back. Fortunately, this episode proves her very wrong, much to our (and her) relief.
- Arc Words: Two Series 9 arc words and concepts are revisited, subtly.
- Hybrid: River Song, the Child of the TARDIS, is effectively a human-Time Lord hybrid, while Word of God confirms that the Doctor was half of the Hybrid of a Gallifreyan prophecy, Clara Oswald being the other half.
- Story: It turns out that River's heard stories about their night together on Darillium being the last one they'll have together. And where "The Zygon Invasion" opened with the text "Once Upon a Time", this one ends on the text "And they lived Happily Ever After".
- Aside Comment: After the Doctor gives an epic speech about how the TARDIS is bigger on the inside, he says "Sorry, I've always wanted to see that done properly" directly to the camera.
- Asshole Victim:
- Hydroflax's head berates everyone and has the list of horrible things he has done quoted repeatedly, so when he's disintegrated later in the episode there's no hard feelings for him at all.
- The entire passenger and crew complement of the Harmony and Redemption are mass murderers or worse, one and all. Thus, the Doctor and River don't feel too bad about not saving them.
- Bait-and-Switch: River stating that her husband is dying can lead many viewers, and possibly the Doctor himself, to assume that she is referring to some past or future incarnation of the Doctor.
- Bald of Evil: Scratch is a ruthless body snatcher, who is bald because of said body snatching.
- Belated Happy Ending: River last appeared in "The Name of the Doctor" (set after her death) two-plus years prior, and while it had been suggested that Eleven had made that date with her on Darillium, it was not depicted onscreen. Turns out that he didn't make the date with her after all, leaving Twelve to do the job in a way that finally grants her the precious, and long, time with her sweetie she'd so long desired.
- Big "NO!": King Hydroflax is in the middle of one of these as his body vaporizes his head.
- Big "OMG!": The Doctor gives an almighty one in his "reaction" to the TARDIS interior.
- Bittersweet Ending: The episode ends with the Doctor taking River to dinner at the Singing Towers of Darillium, the location of the last night they spend together before her death. On the other hand, a night on Darillium is twenty-four years long.River: I hate you.
The Doctor: No, you don't.
- Body Surf: Inverted, Hydroflax's body goes through several different heads over the course of the episode.
- Bookends: In River's last on-screen appearance, we finally get to see the Singing Towers she mentioned in her first one. The episode was nearly this for the whole Moffat era, given her first story was the one Moffat wrote after he knew he'd be getting the top job.
- Bond One-Liner: Discussed.The Doctor: He [Hydroflax's body] had a bad day on the market. [leaves, then returns to observer] Sorry, I appreciate that wasn't really funny but I couldn't help saying it.
- Borrowed Catchphrase:
- When River finally realizes that the man's she's been with all episode is the Doctor, he responds with a "Hello, sweetie." Later, when she asks him whether or not their night on Darillium is to be the last one they will ever have together as she's heard tell of, he can only say "Spoilers."
- The Doctor unwittingly uses Clara's "Seriously?" when River fails to realize his identity after he drops a particularly blatant hint.
- Breather Episode: A story that's mostly comic, albeit with an extremely poignant denouement. After everything that happened in the last series, which had no breather episodes for the Twelfth Doctor, this was warranted.
- Brick Joke: In a "blink and you'll miss it" moment, River pulls a fez out of her bag, eliciting absolutely no response from the Doctor. The Eleventh Doctor loved fezzes so much that Clara once commented "Someday you could just walk past a fez." to which Eleven replied "Never gonna happen."
- But He Sounds Handsome: Inverted. River shows the Doctor her diary (which is almost filled up by this point), and says that he was the sort of man who'd know exactly how long a diary you were going to need. The Doctor replies, "He sounds awful."
- The Caligula: Hydroflax is a brutal, murderous dictator.
- Call-Back: We get to see River's "spotter's guide" for the Doctor which confirms that River knows about all of the Doctor's incarnations by this point, including the War Doctor (who is supposed to be a secret from everyone). In retrospect, this means she only knew of the Doctors of his first regeneration cycle (plus Twelve), as there are no images of any future Doctors.
- Call-Forward: The Doctor finally gives River a sonic.
- River's "Spoilers" and "Hello, sweetie" return — but this time the Doctor gets to say them.
- Although the character likely doesn't realize it, having wiped most of his memories of her, the Doctor nonetheless utters Clara's catchphrase, "Seriously?" in the same way as his lost companion.
- And the show's longstanding "It's bigger on the inside" reaction gets lampshaded and spoofed by the Doctor.
- Character Development:
- The Doctor's actions in the climax and denouement of this story reflect how the events of the final stretch of Series 9 changed him. As a man who doesn't like endings, he was long unwilling to see through his final night with River Song; indeed, had Clara not intervened in the climax of "The Time of the Doctor", his previous self would have died having never having seen it through and likely caused a Reality-Breaking Paradox! Eventually he came to love and depend upon Clara all too much, was Driven to Madness in the wake of her unjust death, and attempted to fulfill a Tragic Dream of bringing her back to life and perhaps staying with her forever — which threatened the universe much the way River choosing not to shoot the Doctor in Series 7 did. But "Hell Bent" ended with him understanding at last that the loss of loved ones can only be accepted; he even endured Mind Rape of his personal memories of Clara to be his best self again and regain his lost sanity. With this, upon realizing how much he's hurt River by never fully returning her love to the point that she doubts he's even capable of the emotion (and realizing that they're Not So Different as he might have once thought) he finally makes an effort to do so. Instead of trying to flee or change fate, he faces it and creates the best final night possible for them. Thus he is finally able to earn his happy ending.
- River gets some too — she's crashed a spaceship into a human colony BUT AWAY FROM ANY PEOPLE so no-one gets hurt, gets on board a ship due to be destroyed by meteor strikes (which results in the death of many bad guys) and, finally, comes to terms with her final night with the Doctor. This also ties into Silence in the Library & Forest of The Dead: She knows the Doctor does love her and that he will come if she asks — so when she gets sent to a mysterious and abandoned library she calls for him, knowing he'll come. Only it's the wrong Doctor who turns up; Ten shows up - she's expecting Twelve, who could easily defuse the matter as he knows to trust River.
- Chekhov's Gun: The bank transfer orb given to River to facilitate payment for her delivery of the diamond. In the climax the Doctor winds up with it and convinces the body of Hydroflax to hook itself up to it. He has realized that the robot will be regarded as, effectively, a would-be hacker by all the financial institutions of the universe once a connection is made. Sure enough, it's attacked by all their respective security systems and the constantly fluctuating stock markets, and the data overload renders it unable to attack.
- Chewing the Scenery:
- River Song's Sickeningly Sweethearts charade, before her actual intentions for Hydroflax are revealed, requires her to be at least as hammy as her royal husband. It helps that she is playing to an intergalactic audience. And, of course, that she's Amy and Rory's child and the Doctor's wife — all three are hammy, so she's picked something up!
- The Doctor is even hammier than usual when faking a newcomer's Bigger on the Inside realisation, not to mention revealing King Hydroflax's head to his admirers in the space liner's restaurant later.
- Christmas Carolers: Referenced; the Doctor has a sign on his TARDIS door that says "Carol Singers Will Be Criticised". Steven Moffat must dislike carolers since Amy Pond threatens them with a water gun in a previous Christmas special.
- Christmas Episode: It's a Christmas special! Though the fact it takes place at Christmas is pretty much waved off after the first five minutes and is only briefly mentioned in the last five.
- Cloudcuckoolander's Minder: With the Doctor keeping his identity secret, he ends up becoming a companion to River herself, who has to deal with the Doctor having too much fun during their shenanigans.River: This is a serious mission in a critical phase. There is nothing to laugh about here.
The Doctor: But we're being threatened by a bag! By a head in a bag!
- Continuity Nod:
- The Doctor doesn't like being sure about things!The Doctor: One minute you're sure, the next minute everyone turns into lizards and a piano falls on you. It's been a long day.
- At one point the Doctor says, in disbelief, "Seriously?" This had been Clara Oswald's catchphrase towards him.
- The Doctor says he can't bow to an important figure because of the strain on his back, just as he did in "Marco Polo". In this case, however, it's more of an excuse for him to segue into a "The Reason You Suck" Speech.
- "Every Christmas is last Christmas."
- River carries a sonic trowel. Her grandfather thought trowels were essential tools.
- Among River's diary entries, Flemming notes Manhattan, the Pandorica, the crash of the Byzantium and Jim the Fish.
- Like Kate Stewart, River thinks the Doctor needs to colour his roots.
- During her rant about expecting the Doctor to find a way around her death, she mentions "the time there were two of you".
- "I hate you." "No you don't".
- The Doctor doesn't like being sure about things!
- Continuity Snarl: The fact River has not yet been sent to her death by the Doctor causes issues with the 2013 Christmas special, "The Time of the Doctor", in which the Doctor prepares to die — and expects to die — at the end of his current incarnation, without having resolved River's timeline. It's difficult to Hand Wave this away when one considers the episode immediately preceding this one was built around the fact that preventing a fixed point in time — which could have happened had Clara not convinced the Time Lords to give the Doctor another life and he'd died without taking River to the Singing Towers — would have been catastrophic for the universe.
- Cool and Unusual Punishment:
- The Doctor leaves a note on the TARDIS saying that carol singers will be criticised.
- Overlapping with Cruel and Unusual Death, River's threat that the next person to use her name will have their organs removed in alphabetical order. Though she never specified which alphabet!
- Curse Cut Short: When the Doctor tricks River into being teleported back into the TARDIS, she shouts "You—!" as she fades out. However, anyone watching her lips move can clearly tell that she's shouting "You bastard!"
- Dark Reprise: The Doctor and River's conversation on Darillium is accompanied by a slow, deep rendition of "The Mad Man with a Box", one of the Eleventh Doctor's leitmotifs.
- A Day in the Limelight: For River Song. It's her first appearance in the series without another companion alongside her, the episode's plot is carried by her, not the Doctor, and the episode sets up some of the details that will lead to her death in "Forest of the Dead", which occurs shortly after the events of this episode (for her). It also reveals more about what she's like, and what she does, when the Doctor isn't around — to both him and the audience.
- Dissonant Serenity: "The starship Harmony and Redemption, minimum ticket price one billion credits, plus the provable murder of multiple innocent life forms. Suites are reserved for planet-burners... Even the staff are required to have a verifiable history of indiscriminate slaughter. This is where genocide comes to kick back and relax. Do try the fish."
- The Ditz: Nardole. In this episode, he's not too bright and something of a Butt-Monkey.
- Dramatic Irony: For the majority of the episode, River didn't know Twelve was the Doctor, not knowing he had gained more regenerations past his Eleventh incarnation. This led to poignant moments when she spoke about him in his own presence. It also led to some amusing moments when she finally realized it.
- Earn Your Happy Ending: The ending of this story may be more bittersweet than outright happy, but it grants both River Song and the Twelfth Doctor a great measure of mutual happiness each of them has long, long needed given their individual journeys — especially after the trope was denied for Twelve in "Hell Bent". Indeed, it's because he's learned so much about love and letting go through his unhappy experience trying to save Clara that he can finally become the sweetie River longed for.
- Explain, Explain... Oh, Crap!: When the bad guys want to use River as bait to lure in the Doctor, she explains at great length how he's too large and important to be bothered with coming to rescue her. She ends saying that the last place they'd find him is next to her when she's in trouble. It's right then that she realizes he's been with her the whole time.The Doctor: [smiles] Hello, Sweetie.
- Evil Is Hammy: The various villains of this episode each embody this trope in distinct ways: Hydroflax's constant shouting, his body's deep-voiced robotic menace, Flemming's sliminess, Scratch and his compatriots' hissing...
- Flying Saucer: At the beginning, River arrives at Mendorax Dellora in a red one that looks like it was taken straight from the pages of a retro sci-fi pulp magazine.
- At the start of the episode, the Doctor is brought to River's doorstep, sporting a haircut and suit. This foreshadows the eventual journey to Darillium.
- When the Doctor gives River her sonic, he quickly grabs it and scans her, foreshadowing their first/last adventure in the Library (and how the screwdriver was holding her telepathic imprint).
- When River's sonic screwdriver is first revealed, the Series 4 soundtrack for the Library actually plays, creating a musical nod and overtone to where this is all going to play out. The initial premiere of the story itself on BBC America was proceeded by a double feature of "Silence in the Library" and "Forest of the Dead" just to bring things full circle.
- Gallows Humour: Discussed — The Doctor, stalling for time when he realizes he's expected to operate on Hydroflax, winds up indulging in a bit of this and notes it probably isn't appropriate under the circumstances.
- Gonna Need More X: The Doctor remarks that explaining how he and River have interacted usually requires a flowchart; after she throws him a conversational curveball, he says "I'm going to need a bigger flowchart."
- Good Scars, Evil Scars: Scratch and the other members of the Shoal of the Winter Harmony have a diagonal scar running across their face. It turns out this is so they can open up their heads; the bank transfer orb is stored inside Scratch's. (The Doctor notes upon the reveal of this ability "you probably shouldn't do that in a restaurant.")
- The Good, the Bad, and the Evil: While the Doctor doesn't see himself as a particularly good man, he's the Good character in this story, compared to River, the Bad girl who's prepared to kill Hydroflax for profit, and Hydroflax and everyone else on board the Harmony and Redemption, who are almost cartoonishly Evil mass-murderers.
- Gorgeous Garment Generation: River is able to change her clothes for an occasion just by spraying herself with a perfume.
- Grand Romantic Gesture: The Doctor not only finally decides to see through his date with River Song on Darillium after centuries of running away from it, but via Stable Time Loop ensures that there's a restaurant overlooking the Singing Towers in the first place. If it's going to be their last night together, it will be as lovely as possible for her.
- The Grinch: Carol singers will be criticised. The Doctor is a temporary, downplayed example as the story begins. He usually loves the Christmas season, but in the wake of all the heartache he's been through since what turned out to really be his "Last Christmas" with Clara, he isn't up for the usual hijinks of A Very British Christmas this year. It takes less time than it took Eleven to get over it in "The Snowmen".
- Hand Wave:
- In-universe, River is more than happy to accept "a thing happening" as the explanation for the Doctor's thirteenth regeneration.
- So if the starship Harmony and Redemption is so exclusive and caters only to mass-murderers... how did River get a ticket and is so familiar with Flemming? Curiously, her "worse than Hitler" reputation from "Let's Kill Hitler" is not mentioned.
- Happily Ever After: Discussed in the closing conversation between River and the Doctor. As a response to the Doctor gently explaining to her that nothing lasts forever and that this trope is a lie people tell themselves, River argues that it isn't about unending happiness, but rather making the most of the time one has. With the revelation that they will have twenty-four years together after so much suffering on their individual journeys, the episode ends on the text "And they both lived happily ever after..." — which dissolves first to "And they both lived happily" and then to "happily".
- Have We Met Yet?: While River Song knows full well who the Doctor is by this point in her timeline, she's never met this incarnation, has no knowledge of his existence since Eleven was supposed to be the last Doctor, and can't recognize her sweetie in him.
- Heartbroken Badass: The Doctor is coming off of a Trauma Conga Line in Series 9 that included Clara's senseless death and his own people betraying him, which drove him to the Despair Event Horizon. He wound up going too far to save her and this led to him getting his memories of her appearance, etc. wiped, though not his adventures with her, so he's currently alone and and a bit broody. The same could be said for River, as it's mentioned that her last trip with the Doctor was the one where her parents died.
- Heel Realisation:
- When River points out that the Doctor's gift of her diary implies he knew exactly how long it needed to be. His response makes it clear he didn't even think of it that way.
- When River gives her big speech about how little the Doctor cares about her, the Doctor can be clearly seen in the background realising what he's done to her her whole life just by being himself — unable to say "I love you", unable to accept endings...
- Held Gaze: River and the Doctor share at least three, with the penultimate one hinting at an Almost Kiss when they're looking at the Towers of Darillium.
- History Repeats:
- This is the sixth Christmas Episode that comes directly after an episode in which the Doctor parts ways with one or more companions, and the second (after "The Snowmen") that sees him in a broody "don't bother me" mood initially as a result.
- This is the third Christmas Episode involving the threat of a spaceship crashing, the others being "Voyage of the Damned" and "A Christmas Carol" (Tenth and Eleventh Doctor adventures, respectively). In fact, the climax of this one is a reversal of the climaxes of the other two — the Doctor and River give up on trying to save the Harmony and Redemption upon realizing that not only will they probably fail, its passengers aren't worth the trouble. As for Nardole and Ramone, the only characters even close to "good" amongst the other people on board (their presence being highly reluctant), they are apparently the only survivors of the crash after a fashion, whereas poor Astrid Peth was one of several good characters who perished in "Voyage of the Damned".
- Once again, the customers of a fine dining establishment — aside from the Twelfth Doctor and his friend — are not who they seem to be at first glance.
- Again, the Twelfth Doctor spends a Last Christmas with a loved one, even quoting that episode in the final scene.
- This isn't the first time the Doctor was at risk of losing his head to an enemy that wanted it for its own.
- River Song is sure that the Doctor has a plan to prevent their night on Darillium from being their last night together, because he always has a plan. In "Face the Raven", Clara believed that too, and thus was certain he could save her from death by quantum shade if no-one else could. Yet he had to admit that he couldn't in that case, and he sadly tells River that he can't change their situation either.
- I Always Wanted to Say That: Before River works out who the Doctor is, she brings him into the TARDIS and he excitedly fakes his own "Bigger on the Inside" moment because he's always wanted it done properly.
- The "I Love You" Stigma: In keeping with a tradition established in 2006 and most recently invoked in the Series 9 finale in which the Doctor does not say "I love you" to Clara but rather uses other phrases, euphemisms, or shows it by his actions, the Doctor never actually says these three words on screen, not even to his wife. The fact this has left River feeling uncertain as to his feelings about her is addressed directly on screen.
- Idiot Ball: Even though she believes the Eleventh Doctor was the last, and is also a bit distracted by the number of moving pieces in her plan, it still takes River a lot longer than one would think to realize the "doctor" she's talking to is in fact the Doctor. Especially with all the hints he drops, such as:River: You are very quick!
The Doctor: Yes... for a Doctor.
River: Yes! [walks away still oblivious]
The Doctor: Seriously?
- I'm a Humanitarian:
- Hydroflax is infamous for devouring his enemies, human or otherwise, sometimes while they are still alive. Which is impressive for a guy without a throat.
- Apparently the Harmony and Redemption has a lot of guests who qualify as this trope, as Flemming initially assumes the Doctor will serve as River Song's meal instead of her dining companion — and was going to suggest he be fattened up via force-feeding first.
- Insectoid Aliens: Flemming and another crew member are blue insectoid humanoids with barbels.
- Ironic Name: The starship Harmony and Redemption sells tickets exclusively to the murderous and genocidal.
- It Amused Me: Since River doesn't think the Twelfth Doctor is the Doctor at all, he acts like a random citizen who got involved in River's antics, including faking his own "Bigger on the Inside moment" when they both enter the TARDIS, simply to amuse himself.
- Karmic Jackpot: A young man on Darillium investigates the crashed spaceship, trying to rescue any survivors. The Doctor assures him there aren't any (and they wouldn't be worth saving anyway), but gives him the most valuable gemstone in the universe for his trouble. Even just the reward for returning it, rather than selling it, is a lot of money. The Doctor's only condition is that he use the money to build a restaurant on the spot — which will quickly earn even more money.
- Kill 'Em All: The luxury starship Harmony and Redemption goes down with all hands and passengers lost. This may be the first time in Doctor Who history where an entire passenger vessel going down with no survivors unambiguously qualifies as a happy ending.
- Laser-Guided Amnesia: Ramone doesn't recall that he married River because she mind-wiped him of that event! (He was getting "annoying", according to her.)
- Lighter and Softer: By far the lightest, wackiest story for the Twelfth Doctor yet, even with its bittersweet denouement.
- Long-Lived: River mentions that she is two hundred years old, meaning, though she gave up her future regenerations, she retains the individual long life-span of a Time Lord.
- Loophole Abuse: Played with. River expects the Doctor to have a way to prevent their inevitable separation. He doesn't, but he does give her the sonic screwdriver that will allow him to save her consciousness in the Library... and in the meantime, this last "night" will last twenty-four years.
- Losing Your Head: When Hydroflax's robot wants to question someone, it removes their head and attaches it to its own body.
- Meaningful Echo: One only the Doctor is aware of, because it's spoken by two different characters. In "Hell Bent", Ashildr told the Doctor that Clara's death on the trap street was both sad and beautiful, "But that's not something you would understand, is it?" When River explains to him that "Happily Ever After doesn't mean forever. It just means time. A little time," she follows it up with "But that's not the sort of thing you could ever understand, is it?" Both women know by this point that the Doctor doesn't like, and refuses to accept, endings. But his experiences in "Hell Bent" taught him that he must accept them, and he does understand what River means now. This is why he's finally seeing through that final night together, which will also be sad and beautiful...but in a much sweeter way.
- Mistaken for Special Guest: The plot kicks off when Nardole mistakes the Doctor for the surgeon River hired.
- Mood Whiplash: On multiple levels.
- The plot goes from slapstick comedy caper to bittersweet romantic ending within the space of five minutes or so.
- That Bittersweet Ending notwithstanding, the episode is shockingly lighthearted and colourful coming directly on the heels of Series 9, a season with quite a bit of horror content, no Breather Episodes, and a climactic quarter that chronicled the Doctor's temporary transformation into a Woobie, Destroyer of Worlds in the wake of a Trauma Conga Line.
- River's Anguished Declaration of Love is followed up by a heartwarming Reveal, and then by some cheeky flirty Snark-to-Snark Combat. Tear Jerker to Heartwarming Moment to Funny Moment in the space of about three minutes.
- Monstrous Cannibalism: It is apparently normal for the children of Flemming's species to eat their mother. On the other hand, this is a ship for villains...
- More Hero Than Thou: The Doctor and River argue over which one of them should stay behind to save the ship. It's subverted when they both remember that everyone on the ship except for themselves is a monster who deserves to die, and escape together on the TARDIS.
- Motifs: River mind-wiping Ramone's memory of their getting married picks up the Series 9 motif of characters remembering and/or forgetting things — often because someone else alters their memory.
- Mundane Utility: After the spaceship has crashed and the TARDIS has landed at the Singing Towers, the Doctor uses a series of quick time jumps to wait out the fire, give the diamond to a random aid worker so he'll build a restaurant, reserve a table at the restaurant four years in advance, and finally take River to dinner. Because of the time machine, this all happens in about two minutes.
- Must Make Amends: The Doctor choosing to see through his final night with River Song after years upon years of avoiding it is clearly his way of making amends for not truly returning her love before, once he's heard her Anguished Declaration of Love. This is in line with his recent Character Development; his parting advice to Clara (as he underwent the mind wipe) in "Hell Bent" included "Never be cruel and never be cowardly. And if you ever are, always make amends."
- My Skull Runneth Over: When the cyborg body connects to the payment orb to access various banks, it is overloaded by the respective security systems and the constantly fluctuating stock markets.
- Mythology Gag:
- The Fourth Doctor was to face a villain named Scratch in an unproduced movie titled Doctor Who Meets Scratchman.
- Doctor, or Damsel in Distress? Now why does this sound familiar...
- A sonic trowel was previously carried by the other Adventure Archaeologist companion, in the novel Professor Bernice Summerfield and the Tree of Life.
- No Endor Holocaust: King Hydroflax's citizens are left hanging after the operation is aborted, with River professing of their loyalty to him, claiming that they hope and pray for his survival. We don't ever see how they'll react when they find out that he's been killed. However, given how cruel and bizarrely punishing Hydroflax is, maybe some of those people will actually be relieved to no longer be under his reign.
- Noodle Incident:
- This is apparently not the first time River has taken the TARDIS without the Doctor knowing and returned it before he realized it was missing.
- River gets Flemming to deadlock the door to the baggage hold with one rhetorical question:"Do you remember that time I was transporting dragon eggs?"
- Jim the Fish gets another mention.
- A Long List of people who married either River or the Doctor includes Stephen Fry!
- Obfuscating Stupidity: According to Word of God from Steven Moffat in April 2017, the explanation for Nardole's ditzy behaviour in this episode is that he's pretending to be so.
- Oh, Crap!: River is quite confident that her deal will go smoothly, despite the fact that the item she's trading is lodged inside a king's head... until she finds out that she is doing business with people working for that king and unaware she intended to kill him.
- Oracular Head: King Hydroflax is a head atop his robot bodyguard, the former ending up stolen by River and the Doctor.
- Prequel: This special sets up the story of, and is set before "Silence in the Library"/"Forest of the Dead" — at least, from River's perspective.
- Portal Cut: The TARDIS has a safeguard in place to avert this by preventing the doors from engaging and the TARDIS dematerializing if it detects a lifeform as being inside the TARDIS and outside at the same time. This prevents River and the Doctor's immediate getaway until Hydroflax's body enters the TARDIS.
- Promotion to Opening Titles: Alex Kingston is finally mentioned in the opener. She carries the episode after all.
- Replacement Goldfish: This is a tricky example. Although technically River Song predates Clara Oswald as a love interest of the Doctor, the timing of this story, coming off three seasons of the Doctor/Clara relationship and airing only three weeks after the events of "Hell Bent", casts River in this role, emphasized by the fact the Doctor has at this point lost his emotional memories of Clara.
- In the Series 6 DVD special feature, a mini-episode entitled "Last Night" a future River said that a future Eleven was taking her to the Singing Towers. River mentions this occasion towards the end of the episode, implying he found a way to wrangle himself out of it. However this episode further retcons the Series 7 episode "The Name of the Doctor" in which the Eleventh Doctor supposedly makes his final goodbye to River's "data ghost" and, more severely, "The Time of the Doctor" in which it is made explicit that the Doctor expects to die at the end of his current incarnation, yet if this is the case he went to his (assumed) death without having resolved River's timeline, which would have caused a universe-ending paradox of the exact same nature of the one narrowly averted in "Hell Bent", the episode immediately preceding "Husbands".
- In "Forest of the Dead" it was heavily implied, if not outright stated, that River's sonic screwdriver was a future version of the Doctor's own sonic screwdriver. Here, it is definitely a completely separate sonic that the Doctor gave her, though it's possibly still made from (what's left of) the old 9/10 casing.
- Similarly, River was completely unprepared for a Doctor who didn't know her in "Forest of the Dead", and notes that the Doctor never told her why he was so sad that night on Darillium. Here, she goes into it knowing it's almost certainly the last time they'll have together.
- Rhetorical Question Blunder: When River threatens the next person that uses her name with having their organs removed in alphabetical order "Any questions?", the Doctor asks "Which alphabet?"
- Right Behind Me: River gives an anguished speech about the Doctor's indifference to her, not realising that he is the man standing next to her. He teases her about it.River: You are so doing those roots.
The Doctor: What, the roots of the sunset?
River: Don't you dare!
The Doctor: I'll have to check with the stars themselves.
River: Shut up!
- Robot Maid: Well, Cyborg Waiter. Hydroflax's robot body survives the spaceship crash along with Nardole and Ramone's heads, the nasty part of the body being gone. They then begin working at the restaurant.
- Second Love: Clara Oswald was the Twelfth Doctor's first love, carrying over from Eleven's burgeoning affection for her, but she died and even after rendering her Only Mostly Dead he couldn't keep her without giving up everything that made him the Doctor. In this story, River Song becomes Twelve's second love. Yes, Eleven was the man who married River, and they had offscreen adventures together... but after all that, it turns out that River still never believed the Doctor truly loved her. As soon as Twelve first recognizes her, he's delighted to have crossed her path again, is subtly jealous of her other husbands, and at last returns her love in ways that Eleven could not, and both end up bittersweetly happy for it.
- Serial Spouse: Both the Doctor and River, to the point where the lists overlap at least once (Cleopatra).
- Ship Sinking: While the Doctor and River reel off their respective lists of romantic partners, Romana (who until River came along was arguably the closest to being the Doctor's romantic partner) isn't mentioned. So that one time they got married isn't canon.
- Shoo Out the Clowns: The hammy villains are all destroyed or nullified when the climax is done and dusted, allowing for the denouement to focus on River and the Doctor's bittersweet night together. However, one clown stuck around; a loose end is tied up with quieter humour with the reveal that the body of Hydroflax was pulled from the wreckage, and with its original AI gone it's now jointly controlled by Ramone and Nardole, serving as a waiter in the restaurant at the Singing Towers.
- To Red Dwarf: The Doctor's antlers are not holographic, they're hologrammatic.
- To Star Trek: The cruise ship is traveling at "Warp Factor 12".
- Pointed out in New York Magazine's review is that King Hydroflax's line "Come to me, my body!" is a lift from The '80s B-Movie Sword of the Valiant: The Legend of Sir Gawain and the Green Knight.
- To Mae West — when River catches the diamond in her cleavage, she brags about being good. The Doctor's response? "I'm not sure 'good' is the word." In other words, goodness had nothing to do with it.
- Sickeningly Sweethearts: Subverted. River and King Hydroflax's relationship looks to be an over-the-top version of this, and the Doctor (already feeling cuckolded) is unable to contain his disdain for River's scenery-chewing declarations of love and oh-so-noble efforts to save her dying husband by any means possible. But it's all an act on her part to get access to that head and the diamond within it, and for it to be convincing, she has to be at least as hammy as Hydroflax is by nature.
- Special Edition Title: As with "Last Christmas", since it's a Christmas Episode the Twelfth Doctor title sequence is decorated accordingly with snow and Christmas ornaments flying through the time vortex.
- Stable Time Loop: Twelve finally takes River to the famous Towers of Darillium and gives her own Sonic Screwdriver, setting up her appearance in Series 4. Even better, he ensures that there is a restaurant at the towers.
- Stealth Pun: Doubles as a Meaningful Name. Hydroflax loses his head, and gains two more, like a decapitated hydra.
- Stop, or I Shoot Myself!: Played with. Hydroflax's robot holds a gun to its current head, one of River's companions, threatening to shoot if her other companion doesn't comply.
- Surprisingly Happy Ending: Prior to River asking how long a night on Darillium lasts, this looks to be another story in which the day is won for the forces of good, yet hope and/or happiness are snatched from the Twelfth Doctor in its denouement, in the tradition of "Kill the Moon", "Death in Heaven", and "Hell Bent". Sure, this episode is largely lighthearted, but so were "The Girl Who Died" and "Face the Raven" before things took a turn for the tragic. But the final few lines of this episode reveal that in its way the last night River and the Doctor have together is really the new beginning of their relationship. As in "Last Christmas", which also teases a sadder ending before a final twist, he has been granted a second chance with someone he loves.
- A Taste of Their Own Medicine: River inadvertently gives the Doctor one by not realising he is her husband, inverting the early dynamic between them where he didn't know she was his wife. She also kisses other people and reveals herself to have multiple spouses — much as the Doctor himself has done!
- Theme Music Power-Up: "A Good Man? (Twelve's Theme)" underscores the Doctor and River's attempts to stop the starliner from crashing and save each other at the same time.
- Throw the Dog a Bone: The Twelfth Doctor suffered horrifically in the final stretch of Series 9 and ended up alone, so now he has a Breather Episode escapade with River Song. Yes, it has a Bittersweet Ending... but twenty-four years together is a juicy bone.
- Unwilling Roboticisation: A humourous version of this happens when Nardole and Ramone have their heads removed and placed in Hydroflx's body. Years later they are still there, but have grown used to this.
- Urine Trouble: Discussed. When Nardole starts to panic, the Doctor tells him to try not to make any puddles. A moment later the Doctor tells him he should get a mop.
- Victoria's Secret Compartment: At one point the diamond MacGuffin is falling through the air and River catches it in her dress, right between her.. ahem... upper lady things.
- Vitriolic Best Buds: The TARDIS has apparently taken to putting Hologramatic antlers on the Doctor's head to cheer him up on bad days... he, on the other hand, has taken to insulting her and calling her a machine. It doesn't turn her against him.
- Wham Line:
- First off:River: Hang on a minute. I recognize that planet.
The Doctor: Well, that's nice! Maybe they'll name the crater after us!
River: That's Darillium!
- Also, the Doctor's response to River asking him how long a night on Darillium is — "Twenty-four years." — is clearly this to her, and to anyone in the audience who didn't suspect that time on that planet might run a little differently than it does on Earth; it significantly shifts the tone of the Bittersweet Ending, as in a sense their relationship is just beginning.
- First off:
- What Happened to the Mouse?: The real surgeon turns up in Mendorax Dellora just as the Doctor and Nardole head off. We never see him again, which becomes particularly odd when it's revealed that he was an accomplice to River's plot to murder the king.
- The World Is Just Awesome: The view of Darillium that the Doctor and River witness is just awe-inspiring.
- Wretched Hive: The starship Harmony and Redemption is reserved exclusively for wealthy mass-murderers, and serves as a business destination for shady dealings. Even the staff members are required to have committed genocide. It also means that, when all the shit inevitably hits the fan, the Doctor and River have no obligations to save them.
- Xanatos Speed Chess: River is pulling this throughout the episode, trying to murder her husband and sell a diamond, then when things go disastrously wrong and the Doctor gets involved (and she knows it's him), they're both planning ways out within minutes of disaster occuring... again.
- The X of Y: The Husbands of River Song. The 126th episode of Doctor Who to bear this naming scheme overall, and the second involving River after "The Wedding of River Song", appropriately enough.
- And they all lived happily ever after...
And they all lived happily