When they reached the TARDIS it was completely covered in ivy.
Danny rubbed his hands together "Right, come on team, let's clear this."
Maebh, feeling better, ran to join them. Clara, the Doctor and Aderyn stood back, watching them work.
"When they're done, you need to get in your box and go." Clara said quietly.
"We're all going. We'll take the kids." The Doctor said casually.
"Take them where?" Clara asked. The Doctor looked at her. She didn't look at him, she was staring resolutely at the TARDIS. She shook her head sadly "What are you going do with them? Leave them on an asteroid? Find a space academy for the gifted and talented? They just want their mums and dads, and they're never going to stop wanting them."
"I can save you and Danny."
"Danny Pink will never those kids so long as he is breathing."
"We can save you." Aderyn said.
Clara looked at her "You don't care enough." She said. "And I don't want you to save me."
"Why?" Aderyn didn't look at Clara, she was trying, for the sake of the Doctor she was trying.
"I don't want to be the last of my kind. You two are already the last of yours. And I've seen what that can do to someone." Clara said.
Aderyn cleared her throat "Right well if this is the end of the world then we're stopping in Victorian London first. I'm not leaving them behind." She went over to the TARDIS to inspect the kid's work. They excitedly took their phones out and Aderyn obliged with their request. She struck silly poses and pulled faces as she took selfies with them. With the job done, Danny and Clara took the children away from the TARDIS and Aderyn and the Doctor retreated into the ship.
"Flame-proof forest. Flame-proof forest." The Doctor muttered.
"A thousand atom bombs and no one hurt." Aderyn said, slapping her forehead.
The Doctor looked at her. She looked at him, waiting for him to realise. "Oh, I am Doctor Idiot!" he shouted "Come on." He ran from the TARDIS.
They ran through the trees, desperately searching for Clara. The Doctor spotted the group before Aderyn did. He called out and shouted at them to come back to the TARDIS. The children were the first to turn and run back to the Doctor. Clara and Danny followed somewhat reluctantly.
Back in the TARDIS, the Doctor walked quickly, making several laps of the console before surveying the people before him.
"It's there on the screen, look. Big solar flare headed this way. A thousand kilometres a second. Coronal mass ejection. Geomagnetic storm. It's huge. It's brewing up a solar wind
big enough to blow this whole planet away. I assumed your teachers have mentioned this?"
Clara crossed her arms "I thought it would spoil an otherwise enjoyable walk."
"Okay. Okay. Well, this is the bad news. The good news is, it's happened before. And you're still here. The Tunguska Blast, 1908. That should have blown the whole planet off its axis, but it didn't. It knocked a few trees over. Well, a few tens of thousands of trees over. Brazil. Same story. Earth should have been smashed, but it wasn't. What do these things have in common?" he said.
"They're really scaring us?" Ruby guessed.
Aderyn put a gentle hand on the Doctor's arm "Maybe you should let me do this. They're just kids after all." The Doctor opened his mouth to protest but Aderyn raised a hand to hush him "They're kids that are nothing like I was at that age."
He sighed "Fine."
"Oi, grumpy face, don't strop." Aderyn said with a smile. She then turned to the kids in front of her "Right to explain it better, Trees. Whenever there's a planet-threatening, extra-terrestrial impact, trees. Massive forest, filling the atmosphere with oxygen. Pumping it up like a massive, highly inflammable airbag, so that when trouble hits..."
"We all die." Samson interrupted.
"No, no you don't. The impact burns off the excess oxygen. You have some fairly hectic weather for a few days and some fairly trippy looking sunsets, but apart from that, you will be all right."
"I don't understand." Danny said.
Aderyn rolled up her sleeves "OK, this will be a bit of a test for you. About 450 million years ago, in the Ordovician period, the only life on the entire planet was whatever was in the sea. The air had too much carbon dioxide for human beings to survive. Why?"
"When you say the only life was in the sea, does that include plants?" Danny asked.
"Yes." Aderyn said.
"So there weren't any trees?" a girl asked.
"No vegetation." Aderyn confirmed.
"So," the girl continued slowly "if there were no trees, then the carbon dioxide was too much because there were no trees to photosynthesise it."
"Exactly." Aderyn continued "So, after a while, I forget how long, the plant life evolves and the carbon dioxide levels in the air drop enough for dinosaurs to start to appearing."
"How is that relevant?" The Doctor asked.
"I'm getting there. Now shush, I'm trying to use this as a teaching moment. So, after the Ordovician period is when life finds a way to begin fully. Since the trees grew and evolved, there have been a few times when trees have come in useful. As the Doctor said, there have been a couple of other occasions when there have been solar flares hitting the Earth. Like this clever girl here said," she indicated the girl who had correctly answered her prehistoric riddle, who beamed with pride "the trees changed the atmosphere of the entire planet. Now, when the solar flares hit the Earth the trees change the atmosphere again. The trees will absorb it instead of the carbon dioxide. The Here, which is what the trees are, said that they were called by the sun, the sun that destroys. They are the life that prevails."
"So the trees are trying to protect us?" Maebh asked quietly.
"Exactly. I was wrong. The trees are not your enemy. They're your shield. They've been saving you since for ever. Protecting you from everything that space can throw at you." the Doctor admitted.
"The wide ring. The red ring. In the museum, Ruby saw a cross-section of a tree. One of the rings was wider than the others, and red." Clara said.
"Atmospheric dust." The Doctor explained "captured by the trees. The fingerprint of an asteroid. Happy Red Ring Day."
"I don't get it." Ruby said loudly "If they're good, then why are we chopping them down?"
"What?" Aderyn asked.
"The Government are sending out defoliating teams. They're dropping chemicals on them right now." Danny explained. He showed Aderyn his phone where he still had the news story loaded on the screen. Aderyn swore under her breath.
"What is it with you people? You hear voices, you want to shut them up. The trees come to save you, you want to chop them down." The Doctor shouted, waving his hands in exasperation.
"Or you think it's the end of the world." Clara said.
"I did admit I was wrong." He snapped.
"We've got to stop them." Aderyn said "we could do something. We could call every phone on the entire planet at the same time, tell them to leave the trees alone."
"Is that possible?" Clara asked.
"Yes. Yes it is." The Doctor turned to the console and began to work.
"Can I do it? I started it. I should finish it." Maebh said.
The Doctor turned and looked at her carefully. He smiled "Class project. Save the Earth."
Aderyn retrieved paper and pens from her room and the group of children sprawled out on the console room floor. Aderyn eventually gave in to their pestering and sat with them, occasionally correcting their use of certain words.
"I think that's it." Maebh said triumphantly.
Aderyn stood "Right then, Allons-y." The children frowned at her "It's french. It means let's go." She added. When she turned to the console, the Doctor was frowning at her.
"I wish you'd stop saying that." He said. She simply smiled at him.
The Doctor looked down at Maebh "Are you ready"? She nodded and the Doctor flipped a switch.
Every mobile phone in the TARDIS rang loudly. Aderyn watched the scanner screen as it showed her every phone on the planet ringing simultaneously.
"Essential services have been disrupted due to an unexpected forest. We'd like to reassure you that the situation will be rectified very soon. Please don't be scared. And please don't chop, spray or harm the trees. They're here to help. Be less scared. Be more trusting. Oh, and Annabel Arden, please come home." Maebh said. Her hands shook as she clutched the paper in her hands, her eyes cast down, reading the words with determination. When she finished, the Doctor flipped the switch again and looked down at her.
"That was good." he said.
"Now we just wait for the rest of the world." Aderyn said "Either way, it's a lovely day out there and I'm going to make the most of it."
The children followed Aderyn outside and, after a few minutes, the Doctor, Clara and Danny heard shouts and laughter. They looked out of the door to see the children and Aderyn running around.
Clara and Danny let them enjoy themselves for some time before finally deciding it was best to take them all home.