In the metal restraints of a broken floor in a burning building on an exploding planet, the Doctor had finally accepted she would die. She'd faced oblivion so many times by now – and hopelessness almost as many – that she'd thought she'd known every form of despair. But somehow this one still felt a little new: her enemies winning utterly, crushing her to nothing until even her memory was gone. For a new Doctor to rise, the old one would have to be scrubbed out of existence.
She thought about her last words, and decided not to say any. Someone might find them out, and complain that they weren't very good. It wouldn't do after so many lives, to end things with terrible words.
The fire was blazing all around her, and she pretended she was at peace. Hopefully she'd die extremely soon. She'd not be able to pretend for very long.
She felt herself begin to black out as the smoke scorched over her body. For a moment she saw a hallucination of Chris and her mother, peering over her behind the soot and flames.
"Chris," she said. "I couldn't save you. And I'm sorry."
The hallucination looked a bit put out.
"I'm saving you," it said. "Don't assume it's the other way round."
"You're not a hallucination!" said the Doctor, a part of her thinking that those would be very bad last words.
"No," said Chris. "I asked Mum if you might be, back on the TARDIS. But she thought I was being silly."
"The TARDIS?" said the Doctor. "You followed me from there? But you'd've died."
"We came here through a wood that you didn't understand," said Chris. "You know a lot, but there's still lots you don't know at all."
She snatched up the sonic screwdriver that had fallen to the Doctor's side, pointing it at the restraints that held her friend to the ground.
"It's no good," said the Doctor. "You'll never be able to use a device like that"—
She hadn't finished talking before the restraints sprang open with a clang.
The Doctor looked up at Chris, her whole face a moon of astonishment.
"That isn't possible," she said. "You shouldn't have been able to do that."
"It's not difficult," said Chris, giving the screwdriver back.
"Yes it is!" said the Doctor. "It takes a Time Lord years just to shape and modulate the sound"—
"But I'm not a Time Lord," said Chris. "I'm a little girl. And I'm tired of you telling me what I won't be able to do."
The Doctor looked stunned, like an ant had told her it could drive a car.
"Get up," said Chris. "I can't save you if you keep lying on the floor."
"Yes," said Lorna. "You can't just lie around here all day. The planet's about to explode."
Their friend got up from the cracked and blackening floor. Now she was able to turn round, she could see a place where the fire changed into orange leaves, which slowly blended to the greens and browns of a forest. A door that hadn't existed, opening to a place that shouldn't be there. They'd found a way out— it was completely impossible, but they had.
"Don't think about how this shouldn't be happening," said Lorna. "Just run. It's what you'd tell us both to do."
"Into that forest?" said the Doctor. "It isn't going to be safe. Lorna, someone's taken my name, and now he'll be taking the Earth. And he'll take the whole universe with it, before he's done. Wherever that wood is, it won't be a place we can hide."
"Can you get us back to the TARDIS?" Lorna asked her daughter, ignoring the Doctor completely.
Chris paused for a moment, genuinely considering it.
"I think so," she said. "Yes."
"That's not possible," said the Doctor. "I mean, I said that last time and it was; we had that thing. But the TARDIS is still on this planet"—
"The wood, you big numpty," said Lorna. "It's the one that's inside your old box. And don't go saying that's impossible too," she added as the Doctor began to open her mouth again.
For the briefest moment her friend looked stunned— and then, despite everything, she began to grin.
"Bigger on the inside," she said. "And I never knew how big it really was. It's my turn, isn't it? To be astonished by the world."
"We need to get away from here," said Chris. "We need to run."
"My turn to be told that, too," said the Doctor.
The three of them ran from the planet and into the wood, the entrance vanishing behind them as they fled. The forest was sealing away that burning world before its flames could spread to the trees: but it needn't have bothered, because they were on fire now too.
"It's burning," said Lorna. "All of time and space."
"This forest is all of time and space?" puffed the Doctor as smoke rose all around them.
"Don't say that's impossible, too," said Lorna.
"I wasn't going to," she said. "I was going to say I was terrified."
Around them all the trees were beginning to blaze.
"I hope we don't have far to run," said the Doctor.
"We don't," said Chris.
"Good. Because – and I mean this in a very literal sense – there isn't a lot of time left."
A cracking, booming sound was coming from somewhere in the wood.
Through the end of everything the three of them stumbled and ran.