[[WMG:[[center:[-''[[Series/DoctorWho Doctor Who]]'' [[Recap/DoctorWho recap index]]\\
'''Tenth Doctor Era'''\\
'''Series 4:''' [[Recap/DoctorWho2007CSVoyageOfTheDamned CS]] | [[Recap/DoctorWhoS30E1PartnersInCrime 1]] | [[Recap/DoctorWhoS30E2TheFiresOfPompeii 2]] | [[Recap/DoctorWhoS30E3PlanetOfTheOod 3]] | [[Recap/DoctorWhoS30E4TheSontaranStratagem 4]] | [[Recap/DoctorWhoS30E5ThePoisonSky 5]] | [[Recap/DoctorWhoS30E6TheDoctorsDaughter 6]] | [[Recap/DoctorWhoS30E7TheUnicornAndTheWasp 7]] | [[Recap/DoctorWhoS30E8SilenceInTheLibrary 8]] | '''9''' | [[Recap/DoctorWhoS30E10Midnight 10]] | [[Recap/DoctorWhoS30E11TurnLeft 11]] | [[Recap/DoctorWhoS30E12TheStolenEarth 12]] | [[Recap/DoctorWhoS30E13JourneysEnd 13]]\\
'''[[Recap/DoctorWho2006CSTheRunawayBride <<< Series 3]]''' | '''[[Recap/DoctorWhoS30E14TheNextDoctor 2009 Specials >>>]]''']]-]]]
!Forest of the Dead
[[quoteright:350:https://static.tvtropes.org/pmwiki/pub/images/Forest_of_the_Dead_7907.png]]
[[caption-width-right:350:''[[BrokenRecord Hey! Who turned out the lights?\\
Hey! Who turned out the lights?\\
Hey! Who turned out the lights?]]'']]
->Written by Creator/StevenMoffat\\
Directed by Euros Lyn\\
'''Production code:''' 4.10\\
'''Air date:''' 7 June 2008\\
'''Part 2 of 2'''

->'''Donna:''' How about you, are you alright?\\
'''The Doctor:''' I'm always alright.\\
'''Donna: '''Is "alright" a special Time Lord code for... really not alright at all?\\
'''The Doctor:''' Why?\\
'''Donna:''' Because I'm alright too.

JustForFun/TheOneWith [[Film/TheElephantMan the Elephant Woman]]. Also the one where we see an end long before a beginning.
----

Donna, our favourite stroppy Londoner, has been having some funny turns recently. As we all know, she was a bit confused and spent a few years in a mental institution. There, she met a nice man called Lee, and now she's happily married with two kids. But lately, she's been having "lost time", and Dr. Moon says everything is ''fine'', and...

What?

But what about the ''Library'' of the ''future'', and the people-eating shadows, and River Song and everything? And then we see a familiar person in Donna's world: Miss Evangelista, one of the {{Red Shirt}}s killed in the last episode. And she tells Donna that none of this is ''real''.

When Donna rips off Miss Evangelista's veil, it reveals that her face has become glitched. The little girl, watching all this on her TV, ''screams''. So do you, because Creator/StevenMoffat.

Donna and everyone else aren't really in present-day London. They're in a LotusEaterMachine, and the computer is getting a little overloaded. Doing what? Saving all the people, of course... that's where they all went. They got saved... to disk. When the Vashta Nerada arrived, the Library's computer tried to teleport 4022 people out ''all at once'', and the system overloaded. Even the neural echoes of people, briefly captured by their suits' comm systems, get included. Which is how Miss Evangelista now lives on.

The Vashta Nerada usually live in forests. They hatch in trees. Trees... that were made into a planet full of books.

The little girl really was a little girl: related to the founder of the Library, she was merged with the Library's computer as a gift to her when doctors couldn't save her life. Her therapist, Dr. Moon, is quite literally the planet's moon, which contains backup systems that stabilise the computer from above.

While the Doctor, back in the real world, works all this out, a couple more people get eaten by the shadows. The Doctor teaches the Vashta Nerada how to use the suits' comm systems to communicate, but it doesn't exactly help. He does, however, convince the creatures to give him one day, and after that, they can have the planet all to themselves. And River manages to persuade him to trust her by whispering something in his ear...

The Doctor realises that he'll need to pull a HeroicSacrifice to rescue Donna and the rest of the saved people. River punches him square in the face, handcuffs him to a wall and decides to sacrifice herself instead. Because she knows that if the Doctor sacrificed himself this way he wouldn't be able to regenerate, as the machine's continuous shock would kill him permanently. And now she knows that this is not only his first time meeting her, it's also her last time seeing him... and that from his perspective, their entire relationship will have been based on the moment the Doctor saw her ''die''. The Doctor is powerless to stop her, and asks her why she was able to whisper that one word into his ear — his ''name''. His real name. Her only reply is a final "spoilers!", and with that, she dies.

All the not-dead people are transported back to the library. Donna desperately searches for her Matrix-world husband, whom she truly loves. But just when he sees her, he's teleported away to his own home, and she decides he must have been imaginary. The Doctor leaves River's diary and her sonic behind in the Library —

— she knew his ''name''. [[Recap/DoctorWho2015CSTheHusbandsOfRiverSong He gave her a screwdriver.]] Why did he give her a screwdriver? Because the screwdriver has a neural relay with her mind's echo stored inside it. The Doctor races back to the little girl[=/=]computer and plugs in what's left of River. Her echo, and those of her companions who died today, can live on forever in the Matrix system, being able to live out untold billions of books. In a bittersweet way, EverybodyLives.

----
!!Tropes:

* AIIsACrapshoot: Played with. The computer systems for the Library isn't working very well, not because of an inherent design flaw, but due to incredibly unusual circumstances. It's designed to run a simulated world for a single individual, and when trying to rescue over 4,000 people from instant death, the computer "saves" them to that simulated world. The modern equivalent would be to try and run a few thousand copies of a high-end video game off of the same set of servers at your local library. Once that massive drain on memory and processing power is relieved from the systems, the Library seems to work just fine, and even have some space left over for a small handful of people to have their own shared simulation together.
* AscendToAHigherPlaneOfExistence: The people that were eaten continue living in {{Cyberspace}}. WordOfGod is that Moffat considers this to be as much being alive as most of us get. Their consciousnesses exist inside an electronic library containing the sum total knowledge of a huge slice of the Universe. They can virtually go anywhere, be anybody, and experience anything. Sounds pretty good, doesn't it?
* AskAStupidQuestion: "It's a screwdriver. It works in the dark."
* BadassBoast: Indirectly, and the more badass for it:
-->"Don't play games with me. You just killed someone I liked, that is not a safe place to stand! I'm the Doctor, and you're in the biggest library in the universe. ''([[{{Beat}} pause]])'' ''Look me up.''"
* BadassFingersnap: The Doctor does one at the end, to see if it will open the TARDIS doors as River had said earlier. Cue the biggest smile on his face when it does. He does another one moments later to close the doors.
* BecauseYouWereNiceToMe: Miss Evangelista's reason for wanting to help Donna escape her false reality is returning Donna's kindness when she was alive in the flesh.
* BigBad: The Vashta Narada.
* BigNo:
** Donna lets out several when her virtual children disappear.
** Lux, upon being told that in twenty minutes, the Library will crack like an egg. [[TemptingFate He then says Doctor Moon will stop it.]]
** The Doctor, at least four times, after the Girl causes Doctor Moon to disappear and stop the Library's systems from working.
* BigShutUp: The Girl gives one to her father before causing him to disappear with the TV remote. She later does the same thing to Doctor Moon.
* BittersweetEnding: Boy, does this episode scream this.
** River Song, the woman who claims to know so much about the Doctor whilst he himself has no idea who she is, sacrifices herself in front of him to save everyone. On the plus side, she is able to have her echo stored in the library alongside her friends to "live" forever. And River herself said he will see her again soon, but it'll be a past version of her.
** Donna's kids were never actually real and she had to leave them and her husband in that virtual reality. And her husband turned out to be one of the "missing" people from the library, who recognized Donna when she saw in real life. But his stutter stopped him from calling her out properly as he was teleported away shortly after, leading her to believe he was imaginary.
** The Vashta Nerada were not defeated at all, and were able to kill almost all of River's crew (though River still died in the end). They only retreated temporarily, in fear of the Doctor's reputation and threats, and still fester the library after everyone else in the library has left.
* BodyHorror: Miss Evangelista's face is literally glitched. She looks badly photoshopped, or like a walking Picasso painting, which is exactly the point.
* BrainUploading: "Zero survivors, four-thousand twenty-two ''[[ExactWords saved]]''."
* BrokenRecord: "We should go. Doctor!"
* CallBack:
** The "squareness gun" Captain Jack Harkness used in his [[Recap/DoctorWhoS27E10TheDoctorDances first appearance]]. WordOfGod says it is the ''same'' gun — pilfered by River from the TARDIS where Jack left it at the end of "[[Recap/DoctorWhoS27E13ThePartingOfTheWays The Parting of the Ways]]".[[invoked]]
** Donna's line to Miss Evangelista: "If my face ends up on one of those statues..." is this, as at the end of the previous episode, a Node appeared with Donna's face on it, repeatedly saying that Donna had left the Library and had been saved.
* ContinuityNod: The Doctor escaping from being cornered by the Vashta Nerada by dropping through a hole in the floor is quite reminiscent of that time [[Recap/DoctorWhoS27E5WorldWarThree Nine escaped from an impromptu firing squad because he'd been backed up against a lift]].
** A very subtle one: "[[Recap/DoctorWhoS4E6TheMoonbase The Moonbase]]" also had a scene where the Doctor reveals that the enemy are hiding in plain sight inside the room, and pulls aside another character to whisper the information to them.
* CorruptCorporateExecutive: Lux appears to be one of these, [[SubvertedTrope until it's revealed what's really been guiding him this entire time]].
--> '''Doctor:''' CAL is a ''child''? [[PoweredByAForsakenChild A child hooked up to a mainframe]]? Why didn't you tell me this? I needed to know this! \\
'''Lux:''' [[WhamLine Because she's]] ''[[WhamLine family!]]'' CAL: ''Charlotte Abigail Lux''. My grandfather's youngest daughter. She was dying, so he built her a library and put her living mind inside, with a moon to watch over her, and all of human history to pass the time. Any era to live in, any book to read. She loved books more than anything, and he gave her them all. He asked only that she be left in peace. A secret, not a freak show. \\
'''Doctor:''' [[SubvertedTrope So you weren't protecting a patent, you were protecting her...]]
* CuckooNest: Dr. Moon tells Donna she hallucinated the Doctor, but is now cured. She's actually in a LotusEaterMachine.
* {{Cyberspace}}: The core of the planet is the biggest library ever; big enough to hold an entire world.
* DarkIsEvil: The Vashta Nerada, being that they exist in shadows, strip humans to the bone and after killing Anita, they say "We are not kind." It can't get more explicit than that.
* DashedPlotLine: Donna's life inside CAL is a subversion. It looks like we're only being shown selected scenes that take place years apart, but then it turns out that ''Donna'' is only experiencing those scenes as well. Only those scenes exist with nothing in between them.
* ADeathInTheLimelight: With Donna stuck in the artificial reality, River steps up as the companion figure for the last time before she dies in a HeroicSacrifice at the episode’s conclusion. Most of this and the preceding episode is spent exploring their future dynamic and her history with his next two incarnations. Her only consolation is that her consciousness was the only part saved, onto the planet’s “hard drive”.
* DoesThisRemindYouOfAnything: The scene where Josh and Ella disappear from their beds. Donna loses it completely and starts screaming and sobbing. It looks and sounds reminiscent of a kidnapping or, worse, OutlivingOnesOffspring. Granted, they're not real, but Donna thought they were.
* TheDreaded: The Doctor's status as this is such that when he tells the Vashta Nerada to use the biggest library in the universe to look him up, they immediately back off afterwards.
* {{Dreamville}}: Donna's life inside CAL's system is set in a virtual 21st-century suburbia with no memory of her time with the Doctor. All quite idyllic except for the fact that no time is passing between cuts, she's been given FakeMemories to compensate, and her children are completely identical to all the other kids in the neighbourhood.
* DumbassNoMore: Miss Evangelista was a BrainlessBeauty in real life. In the virtual world, she is more like TheSmartGuy. As she somewhat clinically observes, the same glitch that ruined her looks shifted her IQ by several decimal points.
* DwindlingParty: Following the deaths of Miss Evangelista and Proper Dave in the previous episode, this episode sees the deaths of Other Dave, Anita and River. Only Lux is still alive at the end. However, the consciousnesses of the dead still live on inside the Library's data core.
* EmergencyTransformation: Occurs in the backstory. Charlotte Abigail Lux was terminally ill, so her rich family built the Library and uploaded her as the mind of the central computer so she could live forever.
* EurekaMoment:
** "You don't say ''saved'', you say ''safe''!"
** When the Doctor realizes why he gave River his screwdriver, to "save" a copy of her into the virtual world.
--->'''River:''' ''[voiceover]'' Everybody knows that everybody dies, and nobody knows it like the Doctor. But I do think that all the skies of all the worlds might just turn dark ''[the Doctor begins to run back]'' if he ever, for one moment, ''accepts it''.\\
'''The Doctor:''' Why?! Why would I give her my screwdriver? Why would I do that?
* EverybodyLives: River Song's closing monologue is all about these "blessed days" where everyone is saved and everybody lives. Those stuck in cyberspace come back and are re-teleported without a problem. Everyone that was eaten is transferred to the Library's core through Wi-Fi.
* ExactWords: The message sent by the Library as it was sealed off said "4022 people saved. No survivors." It turns out "saved" was meant literally, as in "saved to the hard drive", explaining the seemingly paradoxical statement.
* ExplainExplainOhCrap:
** After taking a glance at the room after tinting Anita's visor black, the Doctor pulls River down into a huddle:
--->'''River''': What is it?
--->'''The Doctor''': (quietly) Look, you said there are five people still alive in this room.
--->'''River''': Yeah, so?
--->'''The Doctor''': [[SpotTheThread So... why are there six?]]
** When the Doctor is able to finally speak to the Vashta Nerada itself, it explains that they haven't ''come'' to the library, they ''were born'' in it:
--->'''Vashta Nerada''': We. Hatched. Here.
--->'''The Doctor''': But you hatch from trees. From spores in trees.
--->'''Vashta Nerada''': These are. Our. Forests.
--->'''The Doctor''': You're nowhere near a forest. Look around you.
--->'''Vashta Nerada''': These are. Our. Forests.
--->'''The Doctor''': You're not in a forest, you're in a library! There are no trees in a... [[EurekaMoment library.]]
--->'''Other Dave''': [[MeaningfulBackgroundEvent (offscreen) We should go. Doctor!]]
--->'''The Doctor''': [[OhCrap Books. You came in the books. Microspores in a million, million books.]]
* FaceDeathWithDignity: Anita, when she realizes she has two shadows, is pretty calm about it. After she's gone the Doctor tells the Vashta Nerada that her bravery even when scared was something he really liked about her.
* FamedInStory: The Doctor exploits this when StaringDownCthulhu, telling the Vashta Nerada to look him up as they're threatening him. They do. They back down ''very quickly.''
* FiveSecondForeshadowing:
** After the Doctor tints Anita's visor black, he looks back towards the other archaeologists, only to hold his gaze towards one spot in the back for a few seconds too long. When he then tells everyone else to step back, [[OhCrap you can see a fifth archaeologist in the background, right where the Doctor was looking]].
** In the scene where Miss Evangelista reveals all the children are identical, if you look closely this can be seen earlier in the scene before she points it out.
** Josh and Ella, Donna's children, have this to say to her after Miss Evangelista reveals the world she's in is not real: "But, Mummy, sometimes, when you're not here, it's like we're not here." "Even when you close your eyes. We just stop." Guess what happens a few seconds later.
* {{Foreshadowing}}:
** ''Dr. Moon'' maintains the dream-world's integrity at several points, but it doesn't dawn on what ''he'' represents until the Doctor is told that the moon that's rising in the sky isn't real, but an artificial ''doctor'' moon, which maintains the library database. He's the virus checker; a therapist for a computer.
** Lux accuses the Doctor and River of arguing LikeAnOldMarriedCouple.
** When River's about to make her HeroicSacrifice, there's this exchange. Think about it ''very'' carefully.
--->'''The Doctor:''' [[TheNthDoctor I'd have a chance!]] You don't have any!\\
'''River:''' You wouldn't have a chance, and neither [[ExactWords do]] I!
** As River is describing the last time she encountered the Doctor before coming to the library, she says "the real you", before correcting herself to "the future you", signalling that it's a different Doctor who gets to know River better and who gets to say the last goodbye.
* FourIsDeath: Other's Dave's line of "We should go. Doctor!" is said four times before the Doctor realizes he was killed by the Vashta Nerada and the words are being spoken through his neural relay.
* FreudianSlip:
-->'''Donna:''' I made up the perfect man. Gorgeous, adores me, and hardly able to speak a word. What's that say about me?\\
'''The Doctor:''' Everything. ''[{{beat}}]'' Sorry. Did I say "everything"? [[DiggingYourselfDeeper I meant to say "nothing". I was aiming for "nothing". I accidentally said "everything".]]
* GallowsHumour: When Anita picks up a second shadow, she uses morbid jokes as a coping mechanism.
-->'''Doctor:''' Can I get you anything?\\
'''Anita:''' An old age would be nice.
* HeroicBSOD: The entire third act is CAL having a mental breakdown after finding out about her reality.
* HeroicSacrifice: River Song wires herself up the Library's computer system to allow it to use her personal memory. This kills her stone dead.
* HiddenHeartOfGold: Strackman Lux, set up as a paranoid, uncooperative type obsessed with patents and IP, but it's all a front to keep CAL safe, who is his child-like aunt. He's actually shown to be quite a nice guy after he reveals what CAL is to everyone.
* HolodeckMalfunction: When the Vashta Nerada hatched, CAL initiated an emergency teleport on everyone in the Library. However, there was nowhere to send them. Thus, she "saved" them inside herself. However, this took up too much memory, making her forget about her status as a computer, so when she begins to remember, things start going haywire.
* HopeSpot: Donna really loves her virtual husband, and promises to look for him in the real world as she's yanked out of the computer system. In the real world as everyone is restored, she asks after him, is told no one by that name was in the Library, and unhappily concludes that — like her children — he was never real. However, ''he'' sees her and tries to call out her name, but is halted by his stutter and is teleported home before he can reach her.
* IconicItem: The Doctor is shocked to find his future self has given his sonic screwdriver to River. As she's about to die, River realizes why.
* IKnowYourTrueName: The Doctor doesn't trust River Song, so to facilitate cooperation she whispers his true name in his ear. This makes him trust her immediately.
* InformedAttribute: CAL "loved books more than anything", but we never see her do any reading. It's {{justified|Trope}} because she's not in her right mind and has forgotten everything about her life before the shadows came.
* InsaneTrollLogic: "If he dies, I'll kill him!"
* KinkyCuffs: Implied.
-->'''The Doctor:''' Why am I handcuffed...? Why do you even ''have'' handcuffs?!\\
'''River:''' ''[smirks]'' Spoilers.
* LeaningOnTheFourthWall:
** The scenes appearing on CAL's TV, complete with music. She, like many of the viewers, spends a good part of the episode clutching a pillow and trying not to scream.
** Time in the computer progresses "like a dream" — people just mention where they're going to be, and then they're there. In other words, it's like television. Cutting between scenes in a conventional way, and then revealing that that's how the ''characters'' are experiencing it, adds a meta level to the are-you-sure-you-know-what-is-and-isn't-real theme.
* LightIsGood:
** Everyone wearing a white suit who isn't killed by the Vashta Nerada. River is probably the biggest example.
** Also the clothes of River, both Daves, Anita and Miss Evangelista after River is uploaded to the Library's data core.
* LightIsNotGood: The white suits and helmets of anyone chasing the group after being killed by the Vashta Nerada, with Proper Dave being the most prominent.
* LikeAnOldMarriedCouple: Strackman Lux interrupts an early argument between the Doctor and River thusly:
-->"Oh, for heaven's sake! We're all going to die, right here, right now, and you're squabbling like an ''old married couple!''"
* LiteralMinded: The computer. When it said "4022 people saved, no survivors", it meant it literally. It saved them to the hard drive.
* LivingShadow: Invisible air piranhas, who are very light-sensitive (or maybe just appear as shadows, and are very slow-moving) but can strip the flesh from a chicken leg in the time it takes to fall to the ground.
* LotusEaterMachine: The world created by CAL is a virtual reality contained within a gigantic hard drive.
* MassOhCrap:
** Everyone when the Doctor points out that although River said there were five people still alive in the room they are in, there are actually six, as Proper Dave has caught up to them.
** The Doctor, River and Lux when informed the Library is going to self-destruct in twenty minutes' time.
* MeaningfulBackgroundEvent: Right as the Doctor is learning where the Vashta Nerada came from, Other Dave starts looking upward in the background before the camera pans slightly to the left, removing him from the shot. He isn't seen again for a couple minutes, [[YouAreAlreadyDead but can be heard saying the same thing four times in a row.]]
-->'''Other Dave(?)''': We should go. Doctor!
* MeaningfulEcho:
** River's end-of-episode speech has her quote the Ninth Doctor: [[Recap/DoctorWhoS27E10TheDoctorDances "Everybody lives."]]
** River quotes the First Doctor upon sacrificing herself, telling the Tenth Doctor that he [[Recap/DoctorWhoS1E6TheAztecs "can't rewrite history. Not one line!"]]
* MeaningfulName:
** CAL is the initials of the girl's full name: Charlotte Abigail Lux.
** Dr. Moon is the doctor moon.
* MediumAwareness: Donna starts noticing the episode's editing when she's in the computer. This is because [[PaintingTheMedium the cuts represent the computer basically teleporting her and giving her fake memories]]. It saves an awful lot of space.
* MissedHimByThatMuch: Lee sees Donna in the library just as she turns and walks away from him. His stutter prevents him from calling out to her.
* MoodWhiplash: A four-layered version of it when River tells the Doctor his own name (although it's not until later that we find out what she said). After a pause, he suddenly starts talking about his sonic screwdriver again. Then Anita [[OhCrap realises she has two shadows]]. Then the Doctor points out [[MassOhCrap that Proper Dave has caught up with them]].
* MoreExpendableThanYou: River takes out the Doctor to do a HeroicSacrifice in his place because he has more heroic saving to do and her diary is full.
* MyGodWhatHaveIDone: The Girl has one after she snaps at her father and causes him to vanish. In response, she hurls the remote to the floor and it activates the Library's self-destruct mechanism.
* NightmareOfNormality: As a result of trying to rescue all four thousand visitors by saving them to her database, CAL has accidentally inflicted this trope on herself, living out her fantasies of being an ordinary little girl in a virtual reality environment.
* NinjaProp: The episode uses {{Jump Cut}}s to transition from a scene to the other (for example, the characters in a house talk about taking a stroll in the park, and we jump to the park). Quite an ordinary way of depicting the passing of time in a TV medium, right? Except Donna realizes that she isn't experiencing at all the time between the cuts, only fake memories. This is her first hint she's inside a LotusEaterMachine.
* NoodleIncident: Both of these would go on to be {{resolved|NoodleIncident}} by later episodes.
** This statement:
--->'''River:''' I'll trust that man to the end of the universe, and actually, ''[[Recap/DoctorWhoS31E12ThePandoricaOpens we've]] [[Recap/DoctorWhoS31E13TheBigBang been]]!''
** River mentions [[Recap/DoctorWho2015CSTheHusbandsOfRiverSong Darillium]] and the Doctor showing up [[Creator/PeterCapaldi in a new suit and haircut]]. The suit and haircut also counts as a BrickJoke.
* NoSympathy: The Vashta Nerada didn't really care that Anita was scared, they just wanted to eat.
* NotNowKiddo: Doctor tries reassuring Dave that he's got things under control, as Dave repeats, "We should go, Doctor!" When Dave repeats it the fourth time, the Doctor goes OhCrap as he realized Dave died behind him in seconds.
* OhCrap:
** The Doctor, when he finally realizes Other Dave's been eaten, gets more nervous.
** Anita when she realises she has two shadows.
** The Vashta Nerada when they look the Doctor up.
* OnlyKnownByTheirNickname: Donna's virtual-reality husband wasn't really named Lee [=McAvoy=] in real life.
* PapaWolf: Technically the little girl for whom Strackman Lux is willing to go to such lengths to protect is his ''aunt'', but she died as a child and maintained that mental state. It plays out the same.
* ParentInducedExtendedChildhood: Played with; the library's central computer CAL is actually a little girl named Charlotte Abigail Lux. Her father [[BrainUploading incorporated her into the system]] in order to save her from a terminal illness, allowing her eternal youth and all the books in the universe to read. For good measure, her family kept her existence a secret in order to prevent her from becoming a freakshow to the rest of the galaxy. As benevolent as this move was, it's implied that CAL isn't happy with it, as her LotusEaterMachine features her living [[NightmareOfNormality an ordinary life on Earth]] with her father (who has been dead for decades in the real world). In the finale, River Song is uploaded to the system after her HeroicSacrifice, allowing her to become a surrogate mother of sorts to CAL.
* LeParkour: In one scene the Doctor essentially follows the Parkour principle of "Getting from point A to point B ASAP" as he runs, jumping over carts and shelves and even just jumping into a hole instead of using the mobile transport platform to save River.
* PercussivePrevention: River punches the Doctor out so she can undertake the HeroicSacrifice instead.
* PinkGirlBlueBoy: Josh and Ella's pyjamas. Also, in the playground, Ella's coat and boots are pink and red, while Josh wears a green coat and jeans. Possibly a subtle clue to show that they're not real.
* PlatonicCave: Charlotte is trapped in one, unable to realize that her world is a computer simulation because of the 4,022 uploaded people taking up too much memory space.
* PoweredByAForsakenChild: The Library exists for the sole purpose of keeping CAL occupied, which makes this an inversion. The Library itself is the inversion — there is a child with a terminal, incurable illness, but her family is rich, so [[BrainUploading her brain is uploaded]] and she is given a library the size of a planet to keep her entertained. However, when something threatened the people in the Library, they all tried to [[TeleporterAccident teleport away at once]] and ended up getting stored in the computer. This starts causing problems for the child, so in a way the lifeboats are PoweredByAForsakenChild.
* QuotesFitForATrailer: The "Next Time" trailer at the end of "[[Recap/DoctorWhoS30E8SilenceInTheLibrary Silence in the Library]]" combines the Doctor asking about CAL, River and the Doctor both saying "Spoilers" and the little girl screaming "No! Don't tell! You mustn't tell!" to create a truly FourthWall-leaning clip.
* RescuedFromTheUnderworld: Getting Donna back out of the computer requires some help from someone who knows the truth of the matter.
* RetroactivePreparation: Used by the Doctor to save River Song.
* SelfDestructMechanism: The Library has one of these. It starts at twenty minutes. Then it will "crack like an egg".
* ShoutOut: Miss Evangelista's glitched face looks rather like a [[Creator/PabloPicasso Picasso]] painting.
* ShownTheirWork: Even for the largest computer ever created in the distant future, 4022 people is an incredibly huge amount of space. ''One'' person is 2x10^45 bits of space. That's 2.27x10^31 ''terabytes'' according to this [[https://www.youtube.com/watch?v=xafTmjEXGU0 Because Science episode]].
* SimulatedFantasyPostApocalypticReality: It's revealed that the [[GreatBigLibraryOfEverything Library]]'s population was saved from the apocalyptic release of the Vashta Nerada by its [[BenevolentAI central computer CAL]] - "saved" in the sense that she literally saved them to her hard drive, where they could live in a comforting virtual reality scenario while they waited to be rescued. Unfortunately, the Library was officially quarantined afterwards, meaning that nobody has even approached the planet for a hundred years, leaving everyone trapped in the VR neighborhood - including [[NightmareOfNormality CAL]] herself [[GlitchEpisode thanks to the strain on her memory]].
* SmashCut: There are lots of them while Donna is in the virtual world. They show that the smashes are missing.
* SmugSnake: The Vashta Nerada get rather smug towards the end, when the Doctor informs that he's going to offer them a deal; they let everyone go, and they get their forests to swarm in for all eternity, which they respond to by saying, "these are our forests, they are our meat." The Doctor warns them again, pointing out that they have made the usually lethal mistake of killing someone he likes, and they start extending the shadows towards him. The smugness is very abruptly broken when he tells them who he is and to look him up. The shadows pause, then very rapidly retreat, with a curt and slightly subdued acceptance of the deal as they ''run''.
* SoundOnlyDeath: If River screams as the energy runs through her, it's drowned out by the energy's noise. Doubles as a GoryDiscretionShot as blinding light obscures her, and later the camera never pulls away from the Doctor as he stares devastated at her body.
* SpeechImpededLoveInterest: Donna's husband stutters. Outside the computer, she takes this to mean she subconsciously wants a husband who can't say anything.
* SpookySilentLibrary: Slightly louder since the last episode because so many zombies are talking in broken records.
* SpotTheImposter: The Doctor does this after Anita finds out she has two shadows. Near the end of the episode, he reveals in a WhamLine that he knows Anita is dead because her suit only has one shadow instead of two, so it's actually the Vashta Nerada talking with her voice.
* StableTimeLoop: The sonic screwdriver, many of River Song's mannerisms and rules, including "spoilers!" and the blue diary, she initially got from the Doctor, who in turn got them from her. Another example is opening the TARDIS with a click of the fingers; the Doctor hadn't even thought of doing that until River mentioned it, but she was remembering how he used to do it.
* StaringDownCthulhu: The "look me up" scene is the Doctor confronting a swarm of living shadows and making them blink. Considering the Doctor's reputation, it's perhaps not surprising that they backed down.
* StunnedSilence: The Doctor's reaction when River whispers his ''real name'' into his ear.
* SubvertedCatchphrase: One only noticeable in hindsight. In many other River episodes, she and the Doctor have a recurring dialogue of: "I hate you!" and an affectionate "No, you don't." In this episode the Doctor replies to River's "I hate you!" with a dismissive "I know!"
* SwissArmyWeapon: The Doctor's got his screwdriver, and River's got ''hers'', which has a red setting and dampeners.
* TemptingFate: Lux says the Doctor Moon will protect CAL and stop the self-destruct. In the next scene, the Girl uses the TV remote to make Doctor Moon vanish.
* TomatoInTheMirror: Cal has a FreakOut when she learns from her nephew that she's a computer reconstruction of a little girl. She accidentally deletes her father and Doctor Moon, which causes her to panic further. It takes River pulling a HeroicSacrifice to calm down CAL, restore her defaults, and restore everyone who was "saved" and not killed by the Vashta Nerada.
* TooSpicyForYogSothoth: When the Vashta Nerada, a pseudo-LivingShadow conglomeration of creatures thats name translates roughly into "The Shadows that melt the flesh", with good reason, which exist apparently ''everywhere'' in the universe, corner the Doctor, he gives the BadassBoast "I'm The Doctor, you're in the biggest library in the universe, look me up" not only does the Vashta Nerada stop for a second, ''but starts backing off as well!''.
* TraumaInducedAmnesia: Of a sort. CAL was forced to save all of the people who tried to teleport out of the Library to her hard drive when the system overloaded, but this used up so much of her operating memory that she forgot the reality of her situation and her current status as a computer.
* TrustPassword: River convinces the Doctor to trust her by telling him his real name.
* {{Tuckerization}}: In the virtual reality, Donna's two "children" are called Josh and Ella. Josh is the name of Creator/StevenMoffat's son, with Ella being a friend of his.
* TheUnreveal: River Song knows the Doctor's real name, but only whispers it to the Doctor. We never hear it in "Forest of the Dead", and still have yet to.
* VictoryThroughIntimidation: The Doctor has no way to physically stop the Vashta Nerada (or at least, none we know of), so he gets them to back off by threatening them with his reputation.
-->"I'm the Doctor, and you're in the biggest library in the universe. ''[[BadassBoast Look me up.]]''"
* VirtualGhost: The final fate of River and her crew is to live forever as data inside the Library's hard drive.
* VirtualRealityWarper: Moon initially appears to be able to fast-forward Donna through her life via jump cut and erase her memories if she happens to notice anything unusual. In reality, Dr. Moon is just a support program for the Library's central computer, CAL; while Moon has a certain degree of influence over things, CAL has full power over the simulation - as evidenced when she [[FreakOut has a panic attack]] and accidentally begins deleting people from the simulation, even deactivating Dr. Moon. Fortunately, once the Doctor saves the day, CAL and Dr. Moon are able to rebuild the simulation so as to provide a comfortable ArtificialAfterlife for the now-digitized River Song and her friends.
* WhamLine:
** "BECAUSE SHE'S FAMILY!"
** "You know what? I really liked Anita..."
** "River, you know my name."
* TheXOfY: "Forest of the Dead".
* YourPrincessIsInAnotherCastle: The Doctor sets down River's diary and sonic screwdriver, leaving them behind to turn and walk away with Donna, as River begins a voice-over. It's all set up to make people think the story will end on that note, until the Doctor thinks of a ''very'' urgent question.

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->''"Sweet dreams, everyone."''
-->-- '''River Song'''
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