When a little girl named Maeve comes knocking on the Doctor’s TARDIS, he finds that a forest has overgrown the city of London overnight. The Doctor, Clara, Danny, and some Coal Hill kids must find out why the planet has been overrun by trees and how it connects to the oncoming catastrophic solar flare.
Maeve runs through the forest, swatting some invisible thing from in front of her face. When she comes across the TARDIS, she knocks on the door and asks for the Doctor’s help. The Doctor discovers that the forest he appears to be in is actually London overgrown by trees. Meanwhile, Clara, Danny, and a group from Coal Hill have had a sleepover at the London Zoological Museum and awake to find the new forest and that they are missing Maeve from their group. The Doctor calls Clara and they all arrange to meet him at Trafalgar Square to collect Maeve, who it turns out is traumatized from the disappearance of her sister the year before and hears voices when she’s not on special medication.
Meanwhile, the Doctor tries to figure out where all the trees come from and gets no readings from them on his sonic screwdriver – which means that they’re apparently just normal trees. Initially he thinks it might just be a natural global catastrophe like the ice age, then he thinks that maybe someone is manipulating time, but when he sees a drawing that Maeve did of a solar flare dated for that day, he believes that she has the answer to the whole thing. Of course, in all the commotion of everyone coming aboard the TARDIS, Maeve is forgotten and she takes off running through the woods again. Meanwhile, an attempt is made to do a controlled burn of the forest, but the trees turn out to be fireproof.
Clara and the Doctor look for Maeve while Danny and the kids wait aboard the TARDIS. When Nelson’s Column falls over, Danny grows worried as the kids stoke his fears and he decides to take them to look for Clara. One the Doctor and Clara catch up with Maeve they get cornered first by wolves and then by a tiger escaped from the zoo. Danny comes along and distracts the tiger with a flashlight, saving the day. Maeve goes running off again, and when they catch up with her she tells the Doctor that she thinks the forest is her fault – that she has thoughts that just come to her and then they come true. The invisible things in front of her eyes are all the thoughts flying around her. When the Doctor isolates them with his screwdriver, they tell him that they are ancient beings that live in the Earth. They heard the call of the sun – the oncoming solar flare – and grew into a forest.
The Doctor comes to believe that there’s nothing he can do to help, that Earth is headed for a natural catastrophic event. Clara lures him back to the TARDIS with the idea of saving them, but then tells him to save himself. Just as they part ways, the Doctor realizes that the fireproof trees are there to help – like a giant airbag to protect the Earth from the solar flare. He tells everyone to come back and they send a message to the world that the trees are there to help and not to cut them down. The solar flare strikes the Earth and the trees absorb the blast, then disintegrate into living thoughts and fly away.
Missy watches the Earth survive the solar flare from a console in an office somewhere and seems displeased, saying ironically “I just love surprises.”
As always, Clara struggles with her feelings for the two men in her life. She loves Danny and finds him attractive and endearing – especially how good he is with the kids – but she finds herself lying to him so that she can see the universe with the Doctor. It becomes immediately apparent that despite Clara’s claims to Danny, that she and the Doctor haven’t spent any time apart at all. In fact, Danny finds last Friday’s homework assignments are sitting in the console room still waiting to be corrected. Danny’s not stupid. He really knew all along that Clara was still traveling with the Doctor. He tells her that he doesn’t care what the truth is, that he just wants to know it. Clara is afraid that she has to give up one to have the other, when in fact neither of the men in her life are putting any such limitation on her. Both Danny and the Doctor even encourage her to be honest with them. She seems to believe that her life would be far more complicated trying to balance her relationships openly, when in fact keeping secrets is what makes things complicated.
Danny’s mainly a pretty simple guy with a few surprises up his sleeve. He used to be a soldier, so he’s surprisingly resourceful, often saving the Doctor and Clara from threats that they are not equipped to handle. I mean, how would the Doctor have escaped a loose tiger? Clara is constantly surprised by Danny as well, impressed with his ingenuity, his genuineness, and how good he is with the Coal Hill kids. Clara is amazed at his lack of curiosity about the universe when he declines an invitation to see the solar flare. He explains that having survived battle as a soldier, what he wants is to see are the wonders right in front of him more clearly – meaning that he wants to get to know Clara and come to understand her more completely, if only she’d open up and let him.
The Doctor actually didn’t do much this episode and didn’t have to do much. He investigates a while and takes a nice stroll through a new forest, comes to the conclusion that the Earth is doomed, but then realizes that if he leaves things alone that everything will be fine. The one thing I found really interesting was a sort of callback to Kill the Moon, where the Doctor claims that it isn’t his place to make historical decisions for the Earth because it’s not his planet. Clara tells him that as long as he makes it his home and breathes their air, that he has as much of a say as they do. When Clara tries to make the Doctor leave, to save himself from the oncoming catastrophe, he says to her that the Earth is his home and he breathes their air – that he can’t just leave like he has no place there. It’s like he’s telling Clara that she was right all along, almost like an apology for how he acted in that episode.
Did Missy think the world was actually going to end? And if so, what was her stake in that happening or not? She didn’t seem pleased that the solar flare didn’t roast the world, so what happens now that the Earth is still intact? Perhaps she was hoping for more recruits to the Promised Land. Which begs the question, what happens to the people who end up in the Promised Land? What might Missy need them for? And if she is trying to bring more people to the Promised Land, was the solar flare actually a naturally occurring event, or was it manufactured somehow by Missy? After all, the Doctor couldn’t detect the solar flare with his instruments until just before it happened. Normally there should be quite a lot of advanced notice for predicting solar flares. Perhaps this one arose without warning, perhaps because it was artificially produced. And what’s with Clara going all evil next week? I honestly can’t see how all this is going to come together, it feels like there’s been so little to go on. I am pretty fascinated to see how it all turns out and whether there are clues that I may have missed along the way. Doubtless it will be a bit convoluted and contrived, but it has some big shoes to fill in that department so I doubt it will be the craziest, most improbable finale we’ve ever seen.