It wasn't rain.
The sound of something scuttling behind Amy and River—it wasn't rain at all. It was something much worse. Amy knew it, and she had known it for a long time. She remarked as such to River.
"I know," said River, peering through the slats of a grate.
"Have you got a plan?"
"Yes." River chewed her lip. "Well."
"What is it?"
"Don't let it get us," said River.
"Oh."
"It's an evolving plan," River explained. "Through here," she said, pointing. "Go on ahead of me; I'll be right behind."
They were very close to the top now. Though the tunnels had gotten increasingly narrow, requiring Amy and River to squeeze through tiny passages like spelunkers, they felt the light-headedness accompanied with reaching a great height. River knew they must be close to the TARDIS. There simply weren't many other places the Gorgorans could have taken it. The top floor of the prison was taken up by a large observation deck. There was a grate every few feet, and now River had to stop and look through each one for any sign of their salvation. If salvation it was going to be.
Meanwhile they were in bad shape, and Amy would count them lucky if they made it out of the ventilation system at all. The air was hot and stagnant. Amy's hands were damp with sweat, making it more difficult to gain purchase on the slick metal. She was taking quick shallow breaths and wasn't getting enough air. Their upward progress had almost halted. And that sound. Amy could hear it drumming on the outside of the ducts. If she put a hand on the wall, she could feel it vibrating the metal. In the last few minutes it had gotten much louder, so that Amy and River had to shout to hear each other.
Amy had to believe that the noise was coming back up through the system. That noise was not on the outside anymore. It was in here with them. It was terrible knowing that something was coming up behind you but not knowing what it was or when it would manifest. The only smart thing was to keep moving away from it, but Amy felt her skin crawl every time she turned away from the sound.
When River grabbed her ankle, Amy swallowed a scream.
"Look," said River, as softly as she could.
With some banging and cursing, Amy turned so that they were both gathered around a vent. Yellow light illuminated their faces. Amy looked out—and gasped.
Just beyond the vent was a very large room. It was the shape of a doughnut. Amy and River were on the outside of the doughnut, hiding in the walls. The donut hole was open—presumably, all the way to the floor. Between the wall and the hole was a flat deck about twenty feet wide. Not far from Amy and River, near the perilous edge, was the TARDIS. Amy could see two armed "motorcycle cops." Probably there were two more on the other side. Amy put a palm against the cold grate, and River reached up to stop her. River shook her head, but there was no need. They couldn't get through this way. They'd be caught immediately. Maybe killed.
River put a finger to her lips, then pointed up. Amy leaned back and looked as high as she could. The room had no roof. Bits of the ceiling lay in fragments on the floor. Overhead, a pale mass seethed, plugging the top like a rubber bung. It was alive and moving. Flesh-like it was, but also segmented like the underside of an insect.
The Gorgoran ship, Amy mouthed.
River nodded, then gave Amy a gentle push, urgency in her face. They needed to keep moving. The rushing and ticking behind them were as loud as ever. Amy turned round and began to crawl again, the urge to speed up conflicting with the need to be as silent as possible.
Another five minutes of painful effort, and they came to another vent. This time Amy got on her knees, crouching low so that River could edge in next to her. This vantage point was hardly more promising. From here they could see the front doors of the TARDIS, its lights as dark as Amy had ever seen them. They were no closer to it. Amy could spot more guards from this direction. They were arranged to protect the TARDIS, and though they were no more alive than robots, there was nevertheless and atmosphere of alarm and confusion among them. They were many, and they seemed to be on hair triggers. Amy despaired.
River seemed heartened, though. She cupped a hand to whisper in Amy's ear.
"Get out your key."
"What?"
"Just do it." River took her gun from her side and heated it up.
Amy lifted her TARDIS key over her head and held it in her palm. Its weight was warm and familiar in her hand. River grabbed it, then made Amy hold it between her index finger and thumb, like Amy was about to open a lock. Amy did as she was told, but frowned at River. Why was this any better than the other direction?
River placed the bell of her gun against the grate. "It's going to be loud. Don't be afraid. When we get out there, you run for that door. Don't stop till you're inside the TARDIS."
"What are you doing?" said Amy in a harsh whisper.
River held up a finger. "Listen."
"For what—"
River cocked her head. "Do you know what that is?"
The skittering sound was no longer behind them. It was here. Amy looked over River's shoulder and saw a river spilling toward them. It seemed to be made up of a bunch of tiny little creatures. They scattered the dim blue and golden lights, savagely beautiful.
River's showed her teeth in a predator's smile. "That's timing."
Amy shuddered. Her heart drummed fear through her veins, but River's bright-eyed look rooted Amy where she was. Don't panic, she told herself again and again. It will be all right. She gripped the key between her slick fingers.
The swarm was almost upon them. River caught Amy's stare and shook her head.
River mouthed, wait.
The tiny creatures reached the tips of River's shoes. River winced and set her jaw against the pain. She threw an arm over her eyes and pulled the trigger.
The grate exploded with a tremendous amount of light and noise.
Amy was poised to move, and she threw herself through the tiny opening. She kept close to the floor and clambered left. River was right behind her. River got up at at once, pulled Amy to her feet, and gave her a push. At the same time, she aimed above her head and fired again. There was a hum and another explosion. Slime and goo rained down on them. "GO!" River shouted, pointing the barrel of her gun toward the TARDIS doors.
The glass spiders spilled out of the grate behind them. Amy kept the TARDIS key tight between her fingers and ran toward the door, her eyes on the tiny keyhole. If this was going to work, Amy needed aim as perfect as River's, and she needed to shift as fast as the Doctor ever had.
The spiders were not built to think, nor to determine friends and enemies. They sought only heat and fear, and their only motivation was to rip and tear; they did not even eat. The Gorgorans could make things out of air, but they made nothing that lived in a proper sense. River knew this instinctively and was now poised to turn it to her advantage. The spiders swarmed over the patrolling guards and tore them apart. The guards did not scream, as people might. They had no mouths. They fired into the swarm and when it got to be too much, they staggered.
Without stopping, River fired a few well-aimed bolts at the guards around the TARDIS, and in turn they concentrated their fire on her. Charges zinged by as River ran after Amy, the spiders at their heels like an invading army.
Amy didn't stop when she reached the TARDIS door. She slammed the key into the lock and twisted it and slammed the door open. When she came through—the walls of the time machine opening around her like a dream—she whirled. "River!" she shouted.
River ran toward her, firing rapidly into the Gorgoran ship as she ran. The spiders pooled around her feet. They reached the threshold at the same moment. River tripped on the edge and stumbled inside. Amy slammed the door behind them.
A few spiders skittered around their feet. Amy moved to stomp them, and River, who had fallen to the floor, crushed one with the butt of her gun. Both of them were dreadfully aware that the evil little things might be shredding them right now, if the plan had gone even slightly wrong. But it was no matter; once the TARDIS doors were closed, the Gorgorans' weapons were useless. The spiders disintegrated into their elements, and Amy ground dust and sand under her heels.
They heard scratching and thumping on the box outside, but in here they were safe as turtles in a shell.
"Okay." Amy leaned against the door. "Okay." She swallowed a few times and gave the TARDIS a weak smile. "Now what?"
River didn't answer. She couldn't. She had followed Amy's gaze up to the glass scaffolding, where the Doctor still laid, limp as a sleeping child, hardly breathing at all.