The Doctor grabbed a map from a bookcase as he passed it. He unfolded it as he went back to the console. He pressed a few buttons and tutted when the console declared they had reached their destination, though they hadn't moved. He tried again. Again, the console repeated that they had reached their destination. He ruffled the map "No we haven't." he snapped "We're supposed to be in the middle of London."
"You have reached your destination." The navigation system said again.
"Stop saying that." the Doctor said. He threw the map, missing the bin he had been aiming for.
"She's only saying that because it's true." the girl said.
"We're in the middle of a forest." Aderyn said.
"Come and see." the girl took Aderyn's had a lead her to the door.
Outside, the girl pointed up. Aderyn and the Doctor looked up. Nelson's Column loomed high above them.
"Ah." The Doctor said.
"We are in London." Aderyn said.
Back in the TARDIS, Aderyn took her phone from her pocket and dialled Clara's number. But instead of ringing, an automated message told Aderyn that the person she was trying to contact was unavailable. She hung up.
"Unavailable." She said "I'll give it a few minutes and try again."
The Doctor was about to respond when his own mobile rang loudly from his pocket. "Talk of the devil." he said when he looked at the screen.
Clara started talking the instant the phone stopped ringing "You're always showing me amazing things. Well, I, Doctor, have finally got something amazing to show you."
"Yes, well, there are some things I've never seen, but that's usually because I've chosen not to see them. Even my incredibly long life is too short for Les Miserables." The Doctor replied.
She smiled, looking at the trees around her "Oh Doctor, you're going to love this."
"Well, when you come to collect this child you can tell me all about it."
Clara's stomach dropped "What child?"
"Young female human. Standard defenceless little girl. Your friend Mister Pink was supposed to be looking after her." The Doctor said casually.
"Is Aderyn there?" Clara said with an irritated sigh "If she is give her the phone." There was a sigh, a rustle and muttering.
"Hey Clara." Aderyn said.
"He said you have a child with you." Clara said, her breath shaking with ill disguised panic.
"Yes we do. She's fine, don't worry. Said she thought you told her to find the Doctor."
Clara let out a long, relieved breath "Ok, good. Who is it you've got?"
"Ah," Aderyn said "I really should have asked her that already." She knelt down so she was eye level with the girl "What's your name?"
"Maebh." the girl answered.
Aderyn smiled and stood again "Maebh."
"Can you keep an eye on her until we get there?" Clara asked desperately.
"Of course. We're at Trafalgar Square. I would say you can't miss us but we appear to be in a forest."
Aderyn handed the Doctor his phone "Okay, Clara is coming to collect the child. Then we'll be on our way."
"In the meantime, let's try and figure this out." The Doctor strode out of the TARDIS, sonic screwdriver in hand.
He climbed onto the plinth of a large lion statue. Aderyn followed him, but climbed higher, lying on the back of the lion, looking up into the sky and at the trees that surrounded them.
The Doctor spun carefully on the spot, scanning the trees.
"Why would there be no reading?" he muttered.
"Because they are actually made of wood. No circuits. No mechanism. Wood. And the screwdriver doesn't do wood." Aderyn said, dreamily.
"I should probably do something about that." The Doctor said, returning his screwdriver to his pocket.
"As confusing as it is, you must admit it's beautiful. I have wondered before what London would look like if there were more trees." Aderyn said.
The Doctor raised an eyebrow at her "You've often wondered what London would look like with more trees?"
Aderyn shrugged "I don't sleep much and I get bored."
"I think you need to find a new hobby."
Aderyn chuckled lightly and went back to staring at the trees. She heard the Doctor leave the plinth and she listened to the crunching leaves under his feet as he walked around. She felt oddly at peace.
She had been paying no attention to the passage of time so had no idea how long she had been lost in her own thoughts when she heard footsteps approaching. Suddenly alert and aware she hadn't heard the Doctor for a while, she held her breath, listening closely to the sounds of people around her. She heard whispered conversation, the words masked by the excited chattering of what was, unmistakably, a group of children. She heard a stick snap and a young girl loudly say "Look, no rings. Trees usually have rings to tell you how old they are. This one's got no rings. Why's that then?"
Aderyn let out her breath. Without looking around she knew this would be Clara, Danny and he school kids they were chaperoning. She was about to sit up and swing herself from the lion when she heard the Doctor emerging from behind the TARDIS.
"The rings mark the years of growth. One ring for each year. This grew up overnight." He said.
Aderyn quickly dismounted the lion and smiled at the shocked faces of the school children.
"That whole tree is the result of just one night's growth, and they're still growing." She said.
Clara smiled broadly at the sight of Aderyn and the Doctor "Everyone," she said "This is the Doctor and Aderyn. And they're going to sort everything out. That's what they do."
The Doctor's air of smugness seeped away "Well, having looked at things, I think, probably, the answer to that is no."
Clara laughed nervously "He always says that. He's really clever. Aderyn?"
Aderyn scratched the back of her head "Can't say. I haven't even begun to figure this one out yet. I usually wait till he starts rambling then go from there."
"I am very clever." The Doctor said, some of his smug superiority returning "but what good is clever against trees? They don't listen to reason. You can't plead with them. You can't lie to them. They have no moving parts, no circuits. This is a natural event. And I don't ramble."
"You do." Aderyn said.
"No I do not. I explain things." The Doctor said defensively.
"Now is not the time to discuss that you ramble, Doctor." Clara said, her voice raised ever so slightly.
"Okay," Danny said, sighing heavily "How can it be natural for a tree to grow in one night?"
Aderyn shrugged but the Doctor used it as an opportunity to restore their faith in his cleverness "Exactly what they said about the Ice Age. How can whole glaciers just pop up out of nowhere? Well, they just did. That's how this planet grows - a series of catastrophes. Farewell to the Ice Age. Welcome to the Tree Age. Possibly. When the Ice Age was here, you lot managed to cook mammoth. Now there's a forest, you'll just have to eat nuts."
"See. You're rambling." Aderyn said.
"That is not rambling."
"Knock it off you two." Clara said.
The Doctor stomped away heavily to look at the trees again. Again, Aderyn scratched the back of her head. "You may need to give us a minute to figure this one out. Let's get everyone into the TARDIS. She snapped her fingers. The group cooed in amazement at the sight of the console through the TARDIS doors. "Everyone in."
A small girl stopped in front of Aderyn "If you're supposed to be clever but don't know what's happening, are we all doomed?"
Behind the girl, Aderyn saw Clara raise a warning eyebrow at her.
"What's your name, kid?" Aderyn asked.
"Ruby."
"Well, Ruby, the thing about clever is that sometimes clever takes time to kick in." Aderyn gently ushered Ruby into the TARDIS. Aderyn was about to go in herself when the Doctor bounded suddenly up to her. Stopping in front of her like an enthusiastic child.
"Time." He said loudly. Aderyn walked into the TARDIS and up to the console.
"See." She said to Ruby. "It get's there eventually." she then looked round at the Doctor "Time?"
"Time." he repeated.
"Yes I got that the fist time."
"A tree is a time machine. You plant a little acorn in 1795, and in the year 2016, there's an oak tree, there, in the same spot, with a tiny little bit of 1795 still alive inside of it. You can't create an overnight forest with extra special fertiliser. You have to mess with the fabric of time. And communicate with trees."
"So you're saying it's an act of aggression? By trees?" Clara asked slowly.
"But trees clean the air." Ruby said louder than Aderyn felt should have been possible.
"Does this kid have an inside voice?" Aderyn asked.
"Well done Ruby." Clara said "Someone or something who's trying to scrub the atmosphere before colonising or invading. Ah, yes, Doctor, Aderyn. Ahem. This is Coal Hill Year Eight Gifted and Talented Group." The group of kids looked nervously at the Doctor an Aderyn.
"Uh, hi." Aderyn said.
The Doctor paid them no mind "These trees all appeared at once. That wasn't a coincidence. There's no such thing as an arboreal coincidence. Something, someone has coordinated this. To coordinate, you need to communicate. Every communication channel on the TARDIS is open, and nothing."
Danny drowned out the discussion Clara, the Doctor and Aderyn appeared to been having. He'd only seen the inside of the TARDIS once, and that had been from outside. He looked around the room, gently reminding himself of everything Clara had told him about how safe the TARDIS was and what it was like to be inside it. He spotted a stack of school books and picked one off the top. He flicked through it. Maybe they were old ones that Clara had left behind and forgotten about. After all, she did say she didn't travel with the Doctor anymore. But they were all dated in the last few days. He went back to the beginning and flicked through the book again. Each page had an angry looking sun in the corner that was shooting zig zag sun beams down upon trees. He closed the book looking at the name on the front, then he looked around the group in front of him. He put aside his annoyance at Clara's lies for the moment. He walked up to her and handed her the book, pointing out the drawings in the corners.
"Where's Maebh Arden?" he asked.
Clara looked around the room, but there was no sign of her "Where is she? I asked you to keep an eye on her." She hissed at Aderyn.
"She stayed in the TARDIS when we went outside. Doctor, did she pass you while you were outside?"
The Doctor smiled guiltily "I wasn't paying attention."
"She should still be in the TARDIS somewhere. She may have decided to go exploring. Let's see if she can find her." Aderyn said. She fiddled with the console, eyes glued to the scanner. She did a quick headcount of everyone in the console room then sighed "She's not in the TARDIS. Scanners are only picking us up."
"Oh, my God. Maebh's gone. Maebh's lost in the forest. Maebh's going to die!" Ruby yelled.
"Seriously, inside voice." Aderyn snapped.
"Ruby, that's enough." Clara tutted.
"We need to find her." The Doctor said, flipping through the pages of the book.
"Yes, I know that we have to find her. Doctor, listen to me. Her sister went missing last year. She's on medication. The child is barely functioning. She hears voices. She's very vulnerable." Clara said quickly.
"What do the voices say?" the Doctor demanded.
"I don't know. She takes tablets and they stop."
The Doctor let out a long, low breath "You people. You never learn. If a child is speaking, listen to it."
"Yeah, like you listened to her."
"Danny, please don't start." Clara said.
"He's right. She was trying to tell me something and I ignored her. Maebh Arden is tuned to a different channel. She can lead us to the source, to the heart of the forest. We have to listen to her. We have to find her." The Doctor said. He stuffed his hand into his pocket.
"Doctor, not everything can be fixed with a screwdriver. It's not a magic wand." Clara said.
The Doctor pulled his sonic screwdriver from his pocket "Does she have a phone?"
"Well, yes."
"Do you have her number?"
"Of course. But-"
The Doctor held out his hand and Clara handed him her phone. He sonicked her phone and smiled "Maebh Arden. Five hundred yards south east of here. I'll go get her."
"I'll come too." Danny said.
"Oh, I can go." Clara said quickly and turned to follow the Doctor, who had headed for the door.
Danny grabbed her arm "You haven't seen him for months? You didn't even say hello. You just sprung straight into action. Special unit." Clara looked at Aderyn, guiltily pleading for help. But Aderyn wasn't looking at her. She was wiping fingerprints from the console with the sleeve of her shirt, purposefully not looking at Clara.
"It's difficult to explain." Clara said quietly.
They looked around when the door creaked open and the Doctor stepped back into the TARDIS. He looked at the group of children and pointed a threatening finger "Hey! Do not. Touch. Anything. Anything. Addy, make sure they don't touch anything." he then left quickly.
"See? Someone needs to go. Child protection." Clara said. She shook her arm from Danny's grasp and left.
"Why am I staying behind?" Aderyn snapped.