The one with the voice of Peppa Pig.
Written by Frank Cottrell-Boyce.
We open in a jungle, where a child in a red hood runs through the woods and finds a magical blue box. How very fairytale.
The Doctor's inside, and a bit aggrieved (it's his default state now), but even though the girl hasn't got a Doctor's appointment, he lets her in anyway. Eventually, he figures out she must have a name and asks it — it's Maebh. Maebh's one of Danny Pink's students from Coal Hill, who appears to have gotten lost.
She's also surprisingly unflappable when it comes to the TARDIS's famous dimensional disparity. After all, you can't know everything. Even the Doctor can't — he was aiming for London, and the TARDIS keeps telling him he's there, but that can't be right! This is a forest planet, maybe this is that planet of shrubs —
... oh. OH. OK, so this is the Planet of Pudding Brains.
All that "civilization" and "having cities" stuff humanity's been doing for the past few millenia's just gonna have to stop right there, because the trees have moved back in. Why? Maybe the plants are invading –- it's happened before. Or something's trying to terraform the place with forests so they can move in later –- again, wouldn't be the first time...
To properly find out, the Doctor's going to need Clara. She's just come out of a school sleepover in a museum, with Danny and her class in tow, and she's a bit surprised at all this wanton afforestation too. After a quick phone call to find out the Doctor's got Maebh, Team Coal Hill heads out to pick her up, while the Time Lord and child try to figure out what the hell's going on.
These aren't your grandma's woods. There's a Tyger and some wolves, and something far more fearful than symmetry — there's a solar flare on the way, just like the one that scorched the Bank of Karabraxos. Soon the whole planet'll be burning bright.
Everyone's hands, and eyes, and all the rest of their bodies, are very, very mortal...
- 20 Minutes into the Future: The Doctor states that the year is 2016, establishing a two-years-ahead timeframe for the modern-day episodes featuring Danny and Coal Hill School (and consistent with an earlier episode, "The Caretaker", taking place a year after Danny Pink joined Coal Hill and first met Clara in "Into the Dalek"). This look-ahead timeframe, similar to what previous showrunner Russell T. Davies maintained in 2005-2008, would not be consistently followed, with the later spin-off Class (2016) creating a dating Continuity Snarl.
- An Aesop: "Fear less, trust more" — The trees turn out to be benevolent, and Danny's reaction to Clara's secretiveness is not to make any kind of scene, but to reasonably request an explanation; by the end, Clara is less afraid of being honest with others and showing her imperfections, and while Danny and the Doctor still don't like each other, they have more or less stopped seeing each other as someone who might ruin Clara's life.
- Always a Bigger Fish: It turns out the wolves are running from a tiger. Which makes sense because 9 times out of 10, wolves aren't really interested in being a danger to humans and would rather just avoid them. Big cats, on the other hand...
- Arbitrary Skepticism: Averted. Due to the trees suddenly springing up overnight, the children aren't surprised by the TARDIS being Bigger on the Inside.
- Artistic Licence – Astronomy:
- Solar flares are electromagnetic radiation, not fire. This means they do not require oxygen to produce heat (otherwise, how would they survive the journey through space?). The fireproof trees depicted in the episode would be useless against radiation.
- The atmosphere is not what shields the Earth from flares, but the magnetosphere which is generated by the Earth's iron core.
- Artistic Licence Biology: No attempt is made to explain where the trees got all the biomass they needed to cover the Earth, or how they managed to cover the oceans.
- Artistic License – Chemistry:
- At least it's consistent with "The Ice Warriors". Basic chemistry tells us that even if photosynthesis swapped out every CO2 molecule in the atmosphere for oxygen, levels of O2 would only increase very slightly, as carbon dioxide makes up only a small fraction of a percentage of Earth's air.
- Enriching the atmosphere with oxygen is the last thing anyone should do to prevent a fire. Removing oxygen would be much more efficient (but of course, that way all animal life would choke instead of burn to death).
- Artistic Licence Law: CRB checks (a check of a person's criminal record to verify they have not committed crimes against children) have been superseded by DBS checks. "CRB" is the more familiar term, and still very much in common parlance, so that's the term used in the episode, even though Danny and Clara, as professionals employed to work with children, would be more likely to use the correct term.
- As You Know: Subverted; turns out the children didn't know the world was about to be destroyed, as Clara had been keeping that information from them.
- Big Damn Heroes: Danny saves the Doctor and Clara from a tiger.
- Breather Episode: This episode comes between "Flatline", a scary episode that examines the downsides of Clara's Character Development over Series 8, and the tragic two-part finale "Dark Water"/"Death in Heaven", which ends miserably for our heroes even as Earth is saved. Beyond the spooky fairy tale-esque atmosphere, this episode is much lighter — Everybody Lives, there's No Antagonist, a bunch of cute kids are present, and Clara, Danny, and the Doctor's positive character growth is examined.
- Call-Back: To Clara's "breathe our air" line from "Kill the Moon".
- Chekhov's Gun:
- Bradley's blindingly bright torch. It seems like an unremarkable object at first, just serving to develop Bradley's character as a troublemaker and getting confiscated by Danny when he annoys Samson with it, reasoning that he shouldn't have a light so ridiculously strong simply for his fear of the dark. Then Danny discovers it's really good at blinding tigers, too.
- Fireproof trees. At first it doesn't seem important, but then we learn about the solar flare, and it makes sense that the things preventing it from turning the planet into a raging inferno wouldn't be affected by flames.
- Danny tells Clara to go home and think about what she's going to say to him. She does this in the next episode, with post-it notes.
- Child Hater: The Doctor is the mild version; he finds them irritating and his child-minding skills could do with some work.
- Continuity Nod:
- This isn't the first time the Doctor mistook a plant-ravaged Earth for a different planet...
- The Doctor compares the coming solar flare to the one that destroyed the Bank of Karabraxos in "Time Heist".
- "The Tyger", the poem from which this episode's title is taken from, was in a book that Tommy read at a monastery after getting an IQ boost from a Metebelis crystal.
- Damsel in Distress: The Doctor lampshades Maebh as the "standard defenceless little girl".
- Don't Go in the Woods: Discussed at length and invoked with allusions to fairy tales and lost little girls, but ultimately subverted. The forest is not a monster, it's a shield.
- Easily Conquered World: The Doctor says that if this is an Alien Invasion, they've won already.
- Escaped Animal Rampage: A pack of wolves and a tiger escape the London Zoo due to the sudden, explosive growth of forests and run rampant around central London.
- Extra-Strength Masquerade: Apparently the whole of the world will collectively forget a forest grew overnight and then evaporated. Presumably the damage caused by the trees (such as Nelson's Column and the animal cages in the zoo) will be given some more mundane explanation, the way humanity in the Whoniverse has tended to do for the various alien invasions, environmental disasters, corporeal hijackings or Miracle Day.note
- Everybody Lives: The Doctor initially believes the solar flare will wipe out humanity, but then realizes that the trees popped up to absorb the impact.
- Failed a Spot Check: Clara and Danny somehow fail to notice Maebh has gone missing until the Doctor calls to say she's arrived at the TARDIS.
- Fly Crazy: Maebh keeps waving her hands above her head, trying to shoo away the creatures only she can sense.
- The stuffed wolves and tiger at the museum where the Coal Hill students' overnighter took place, which hint at the upcoming animal encounters.
- The Doctor self-deprecatingly calls himself an idiot, which'll come back in a couple episodes.
- Freeze-Frame Bonus: In one scene a double-decker bus can be glimpsed in the background. Clearly visible on the side of the bus (which in reality was a large cardboard cutout so this was intentional) is part of an actual real-world advertisement for Doctor Who; the ad is actually more noticable in the trailer for the episode.
- Gaia's Vengeance: Subverted, the Doctor spends most of the episode thinking that the trees have covered the world and provoked the solar flare to destroy humanity, but they're actually saving the Earth from the flare.
- Good News, Bad News: The Doctor explains how the solar flare is going to roast the planet, and then assures the kids that there is good news: The trees will protect them.
- Green Aesop: The trees are just trying to help, so stop cutting them down lest some outer space disaster befall the planet.
- Hazmat Suit: Men in fire fighting gear toting flamethrowers are portrayed in the usual menacing way until we find out what they're up to.
- Hitler Cam: Inverted for the Doctor's initial view of Maebh.
- Ironic Echo: For once, the Doctor gets the whole "tricking the companion to get them away" routine we have seen time and time again in episodes like "Timelash", "The Parting of the Ways" and "The Time of the Doctor" reversed on him; Clara has no intention of escaping by herself, but tells him to get them out to get him back to the TARDIS. This prompts him to express how much he has come to value the Earth, echoing Clara's lines from "Kill the Moon", to the point that he refers to the Earth as "his world". This time, he perfectly understands and respects it when she doesn't want to be saved, while she understands that he "can't fight physics" and asks him to leave; the whole exchange shows how much the two have grown to understand each other since "Kill the Moon" and how seeing each other's edgier bits ultimately strengthened their bond.
- Kill It with Fire: Attempted by the government, but the trees contrive to be fireproof.
- Last of His Kind: After observing the Doctor for a while, Clara would rather have herself, Danny and the kids die than let the Doctor save them to become this.
- Leaning on the Fourth Wall: An ad for Doctor Who is clearly visible on the side of a double-decker bus in the background of one of the scenes. See Freeze-Frame Bonus, above.
- Like an Old Married Couple: Clara and Danny arguing over the Doctor. Lampshaded by their students.Bradley: Who said they're in love? Why are they shouting at each other?
Ruby: That's what people do when they're in love. Don't you know anything?
- The above quote also serves as Ship Tease for the Doctor and Clara since that's what they do, too.
- Literal-Minded: Ruby is this in spades, doing a version of the "Find x" gag in a flashback. It's right there on the board!
- Literary Allusion Title: From that perennial source of titles, William Blake's poem "The Tyger". The reference is driven home when the Doctor, Clara and Maebh are menaced by a tiger escaped from the zoo.
- Little Dead Riding Hood: The opening scene is Maebh running through the forest in her red jacket. Later in the episode, she's accosted by wolves.
- The Lost Woods: Apart from having sprung up overnight instead of being older than memory, the forest takes on many aspects of the Lost Woods. At the end of the episode, the Doctor theorizes that the forest that features in myths and fairy tales is a remnant of a cultural memory of an earlier occasion when something like this happened.
- Love Triangle: The off-kilter scenario in which Clara tries to maintain relationships with Danny and the Doctor breaks down as the men discover she's been lying to them both. The Doctor isn't particularly upset, and neither is Danny, who nonetheless effectively gives Clara the "choose him or me" ultimatum and tells her to start telling the truth or they're through, leading to tragic circumstances in the next episode.
- Magical Security Cam: Missy again, this time with an orbital shot of Earth as it is hit by the flare.
- Meaningful Echo: The Doctor pleads with Clara to let him help our planet, saying he walks our Earth, breathes our air.
- Meaningful Name: Maebh — named for a mythological queen of fairies, ultimately helps to establish communications with the fairy-like creatures behind the forest. Her last name, "Arden", is a reference to the famous Forest of Arden in Warwickshire, a former real-life version of The Lost Woods and most well known for being the setting of William Shakespeare's As You Like It.
- Monumental Damage: Nelson's Column falls, nearly hitting the Doctor and Clara.
- Mundanger: The Doctor is visibly nervous when facing a tiger. He also expresses frustration at finding himself up against trees because he can't use his usual tricks — he can't outsmart them, lie to them, out tech them, or even scan them.
- Mundane Utility: An implied one when we see Clara has been marking the children's homework on the TARDIS, presumably because it gives her plenty of time to do so.
- My Nayme Is: Maebh's name is spelled in the original Irish fashion, as opposed to the more usual "Maeve".
- Next Sunday A.D.: The Doctor establishes at one point that the episode is set in 2016, despite airing in 2014.
- Nice Hat: Samson wears a variant New York Yankees cap throughout.
- Nice Job Breaking It, Hero!:
- Nearly happens with the government engaging in deforestation. The Doctor is able to stop this by sending a message across the world.
- Lampshaded by the Doctor when he and Clara observe the flare arriving at Earth, and the Doctor half-jokingly says that it would be embarrassing if he was proven wrong.
- Nightmare Fuel Colouring Book: Maebh's exercise book full of drawings predicting the events.
- No Antagonist: The closest thing the episode has to a real antagonist are non-sapient animals and a solar flare.
- No Medication for Me: Maebh's medication stops her hearing the voices of the the forest, so the Doctor tells everyone to stop giving her tablets.
- No Ontological Inertia: After the flare, all the trees just melt away into fairy dust.
- Not So Above It All: The Doctor's frustrated words about how sonic screwdrivers don't work on trees might just imply that even he isn't completely beyond the Primal Fear factor of the forest; not that extraneous given that Gallifrey was said to have forests as well, whatever fancy colours they might come in. Also, the Doctor yells at everyone that they should listen when a child talks (referring to Maebh), but Danny points out the Doctor didn't listen to her, either. The Doctor concedes the point.
- Papa Wolf: Danny is repeatedly shown to be quite protective about his students, a trait that Clara values and finds attractive.
- Primal Fear: Upon finding herself lost in the forest, Clara specifically notes that she's having a different type of fear reaction from what the situation logically warrants (and she's been in enough life-or-death situations to know what she's talking about). The Doctor points out that "the forest" is the location of every fairy tale that scares human children, and is essentially humanity's collective nightmare. The Doctor himself is not completely immune to it. It turns out that the reason for this instinctive terror is a buried and distorted memory of the last time trees saved them from a terrifying global disaster.
- Ragtag Bunch of Misfits: The Gifted and Talented kids seem to be made up mostly of the weird kids that Clara and Danny thought had something special.
- Recursive Canon: A poster advertising Doctor Who is seen on a bus in the background.
- Running Gag:
- Newcomers to the TARDIS are amazed at how it's Bigger on the Inside but no one asks how, so he explains.
- The sonic screwdriver still doesn't "do wood". No moving parts, you know?
- The Doctor still can't retain Danny's name, nor that he is a math teacher instead of a P.E. teacher.
- Savage Wolves: A pair of wolves hunt Maebh. Then they catch up with the gang... and run past them, ignoring them. Turns out they weren't running after her, but away from the tiger!
- Self-Deprecation: "I am Doctor Idiot!"
- Screaming Woman: It works, enabling the Doctor and Clara to find Maebh when she screams after seeing the wolves.
- Shipper on Deck: The students cheer when Clara and Danny have a Big Damn Kiss.
- Although it isn't seen that way in the episode, the angle from which the Trafalgar Square lion's head is seen in the episode's main publicity shot (see above) makes it look a lot like the face of Swamp Thing. Which is appropriate given the resemblance between the fairy-dust entities and "the Green" in Swamp Thing.
- The Grimm's Fairy Tales of Little Red Riding Hood and Hansel and Gretel get explicitly referenced with Maebh's red coat, the wolves wandering around the woods, and Maebh dropping items to make navigation around the forest easier. The Doctor even namechecks both fairy tales.
- Single-Biome Planet: Earth is temporarily a forest planet.
- Skewed Priorities:
- Zig-Zagged — Clara is trying to investigate the possibly world-threatening Crisis of the Week, while Danny is focused on protecting the children, their immediate responsibility.
- Danny's more upset that Clara has been lying about her adventures with the Doctor then he is happy that an expert is on the case. Also, he's more concerned with Maebh being with the Doctor than lost in the mysterious forest.
- Space Whale Aesop: Psychologically disturbed kids who hear voices shouldn't be given medication, because the voices actually belong to benevolent tree fairies trying to help humankind.
- Starfish Aliens: The trees were created by dust-like creatures which have lived as long as the Earth and can spontaneously grow entire trees worldwide in one night.
- Status Quo Is God: On a planetary scale. The overgrown forest conveniently disappears into thin air once its purpose is fulfilled, and people will also quickly forget what happened.
- Stay on the Path: While drifting into Fairy Tale motifs, the Doctor gives Clara this advice. She says there is no path to stay on, to which the Doctor says means they are lunch for wolves.
- Supporting Protagonist: The Doctor, Clara, Danny and the children have little effect on the overall course of events except for broadcasting a plea not to defoliate the trees. From start to finish the trees have everything under control.
- Reveal Shot: The camera lifting over the trees to show all of London is covered in foliage.
- This Is the Part Where...: Clara explaining to Danny how the Doctor will save the day with a brilliant idea, right as he's explaining how he can't. Then he does.
- Trail Of Breadcrumbs: Maebh drops various items so Clara and the Doctor can find her as she runs to the source of the forest. Hansel and Gretel get a mention.
- True Companions: Danny ruefully recognises Twelve and Clara are this, when he sees yet again how instantly they spring into action together in response to a threat. He's been (somewhat) oblivious to her lies and initially thinks she hasn't seen the Doctor in months, whilst the truth had her having seen the Doctor just the Friday before (and the story allegedly takes place on a Tuesday).
- The Tunguska Event: Apparently a similar incident with solar flares and tree shields happened before.
- We Have the Keys: Clara urges Maebh to climb the fence to escape the wolves. She runs a few feet to the side and opens a gate.
- What Does This Button Do?: As might be expected from a group of children, the TARDIS has lots of fun buttons they feel compelled to play with. Fortunately, doing so does nothing other than annoy the Doctor.
- What Happened to the Mouse?: Or rather, what happened to the wolves and tiger after the forest left again?
- Wild Wilderness: A literal urban jungle created in London, not to mention the rest of the world, when trees appear out of nowhere.