They had been walking for a while, though the end of the corridor still shielded itself from sight. Every few feet they would pass an opening to another passageway, down which could be seen a variety of further corridors, splintering off into a twisting maze. The Doctor insisted on sticking to the central route – there was something too untrustworthy about this house, as though if they ventured down a different corridor they may never be able to find their way back.
"Doctor, wait…"
The words came from Amy. She had stopped, her head bowed slightly, as she tried to listen to something.
"Amy? What is it?" the Doctor asked quietly.
"I can hear something."
"Yeah, I can hear it too." Rory said, craning his head forward slightly to hear the noise better. "It's like-"
"Movement." the Doctor finished. "Like something's approaching us."
Slowly, all three of them looked up, their gaze directed down the corridor. At first they thought all they could see was the darkness that seemed to fill every unattended corner and corridor of the house. But it gradually became more apparent that the darkness was moving. Building up into a gathering cloud, it was swarming towards them, picking up speed.
"Doctor, what is that?" Rory demanded, starting to back away from it.
"Can't be…" the Doctor murmured, almost too intrigued to run from the danger. He grabbed the sonic screwdriver out of his pocket, scanning the pitch black fog that was gaining on them. Flicking his wrist up, his eyes darted over the readings from the screwdriver. In a moment of unwelcome realisation, the Doctor whispered two words. "Vashta Nerada."
"What?" Amy and Rory insisted simultaneously.
"Piranhas of the air! Tiny, microscopic creatures that live in the shadows and eat flesh."
"Do you have a plan?" Amy asked desperately.
"Yes." the Doctor replied, with a false air of confidence. "It basically involves running away while I think of a better plan."
That earned horrified glances from both his companions. The Doctor simply returned their look with a smile, before darting down the nearest corridor, grabbing their arms to drag them with him.
The corridor they had entered was short, splitting into two separate directions after a few feet.
"Which way?" Rory asked hastily.
"Doctor!"
Amy screamed the word, having looked back the way they had come. Rory ran to her side, while both he and the Doctor followed her gaze. Their eyes fell upon the shroud of darkness tearing its way towards them, following them down the short, narrow corridor.
There was no time to think. They ran. Amy took one route, Rory following, and the Doctor took the other. The mass of darkness exploded against the wall where the two routes separated, splitting into two streams of shadows, following both the Doctor and his companions.
The Doctor threw himself around another corner, now having completely abandoned his plan of attempting to stay anywhere near the main corridor. He had to get away from the swarm of shadows and so was taking every deviation possible from the main network of corridors, into the smaller wooden walkways.
Finding a shadowed corner, which he hoped would be free of Vashta Nerada, the Doctor hid, silently, at the end of one small corridor and listened to wind-like gusts of movement that had been stalking him. He could just about make out the passing of shadows as his stalkers continued past the corridor and onwards through the house. He was safe, for now at least.
Vashta Nerada – it didn't make sense. The Doctor's mind was furiously puzzling over it. How could there be Vashta Nerada here? More importantly, how were they involved with everything that was going on? This was way beyond them. They were too primitive to be able to create anything like this. Manufacturing fear, that unrecognisable creature that had attacked them on the floor below – the Vashta Nerada were just one part of a much bigger picture.
Considering the facts, the Doctor quietly moved from his hiding place, continuing down the spider web of corridors, not really looking where he was going. There had to be something else going on here. Some form of higher intelligence, members of a more powerful species controlling this. But what?
"Doc-tor…"
The Doctor froze. A cold, stinging shiver shot down his spine. The voice had come from behind him, accompanied by a mechanical whirring of movement. Something had been watching him from the corridors that splintered off from this one. And he knew what. He could never mistake that voice. That harsh, metallic, grating voice. Slowly, almost shaking, he turned round to confront the one thing he feared more than anything else in the universe.
"Resistance is futile, Doctor! You are now a prisoner of the Daleks!"