Crack.

A distinct sound of something breaking echoed through the cavern, startling Donna out of the doze she was beginning to fall into. The Doctor, who hadn't moved for some time, finally lifted his head.

"Where?" he asked.

After a second, realizing that she couldn't point, she said, "Above us…"

"Directly above us?"

Seeing what he was getting at, she grasped his wrist and helped him to his feet, though he wasn't quite so stiff that he required aid, and guided him to the furthest end of the cavern, several metres away.

When she stopped, he asked anxiously, "Are you sure this is safe?"

"If it's not, it's the closest we can get."

Dust was falling from the ceiling, and finally, finally, shafts of light fell through. Donna let out a cry of joy, clasping her hands together. She could see, really see, and it hurt her eyes a little after the long dark but she didn't care, it was glorious.

More than dust now—stones as big as her head were coming loose and plummeting down to strike the cave floor very near where they'd been resting. Thank God for the Doctor.

And more light, and it was wonderful, and it stretched across the entirety of the cavern and she could see. No squinting, no dimness. She could look around her and really see, and she'd never been more thankful for it.

Which reminded her of the fact that the most wonderful man she'd ever known was next to her right now, blind. She turned towards him, already worried, and when she really took a good look at him it was almost horrific.

His eyes… they were unfocused, milky, glazed over. Those deep brown eyes that held wisdom far beyond his appearance—sometimes, she suspected, too much wisdom… and now they were sightless, dead. He was just staring ahead, unable to partake in her relief.

"Doctor," she said softly, but the falling rocks were making too much of a racket for her to be heard, so she grasped his arm, and he turned his head towards her slowly. He still wasn't focusing on her, and this was even worse than before. Because he was turned towards her, he should be able to see her. He was the Doctor, he saw everything.

But he couldn't.

When the cave was finally quiet, she looked up and could just make out figures. They had created an opening a few feet across, definitely enough for her and the Doctor to get through.

"Doctor," Donna said again, and he moved to face her again. She sent up a silent prayer of thanks that he could still hear her.

The figures above them called down, "Hello! Can you hear me?"

"Loud and clear," the Doctor called back up, and Donna couldn't hold back a smile at finally hearing him sound confident again, "but I'm afraid that won't last long for me."

A moment of silence. And then the figures were scrambling around, frantic and chaotic. Another voice came, "Come over just below us, quickly."

They both stood, and did as they were told. A brief sound of rummaging around. Then, "Catch these."

Two small objects came plummeting down, and Donna raised her hands, nervous about missing. She caught one, and the other one glanced off her fingers and hit the Doctor in the shoulder. He blinked, and looked down in the general direction of where it had landed. "What's that?"

The items were small pouches, made of some material Donna didn't recognize. She opened one cautiously, to find it filled with small objects about the size and shape of contact lenses, but sturdier, with tiny depressions covering them. She handed the pouch to the Doctor and bent over to pick the second one up. "What are these?" she called.

"Put them on your fingers and toes," came the reply after a slight delay, and Donna looked over in confusion at the Doctor, who obviously was not aware of her gaze, and who was already following the instructions they had been given.

"What are—" she started.

"Just do it, Donna," he said, an edge to his voice. "Quickly!"

She complied, remembering how panicked he had seemed. It was strange—after she'd covered one hand of fingers with the strange little objects, she went to do the same to her other hand, and she couldn't really feel them on her first hand anymore. Her fingertips just felt a little bumpy. It was disconcerting, but she shrugged it off for the Doctor's sake.
When she had finished with her hands, she hesitated, and looked over at the Doctor. He was already removing his trainers and placing the objects on his toes. Donna held back a sigh and sat down, pulling her own shoes off.

She stood up when she finished, about the same time the Doctor did. "Now what?" she said, still completely lost.

The Doctor replied readily, as he shoved his shoes and socks into his large pockets, "Show me to the wall. Beneath the opening, the cave wall."

Donna guided him the few steps forward and placed his hands on the wall. He turned his head slightly in her direction, and said only, "Climb."

"Climb," she repeated after a surprised moment. "What, up the walls of the cave?"

"Yes," he answered.

"Like Spider-man?"

"If you like," he said with a little shrug. "Now go! You before me."

Uncertain, she reached out and placed her hand on the cave wall. And she placed the other above it. She braced her foot against the stone, and, not sure what she was expecting to happen, hoisted herself up.

And it worked.

She stayed there, hanging from the wall, stunned. After a few seconds of silence, "Hurry up, Donna!" came from behind her, and the Doctor actually sounded very panicked for a moment, and she hurriedly began ascending the wall. She wondered, briefly, if he had been afraid that his hearing had gone as well.

Donna was already a quarter of the way up. It was incredible; her fingers and toes just stuck to the stone wall. She didn't have to bother with handholds or footholds, she could just go.

She was enjoying herself immensely, though she'd never been one for climbing. It was so easy. But apparently there was no time for enjoyment, because now she was going too slowly for the natives waiting above them and the Doctor was behind her sounding almost hysterical with urgency and that was enough that she practically flew up the cave wall. Before she knew it, she was being helped through the opening and into the light and she tumbled onto the grass, breathless.

The Doctor was right behind her, and the people around them hastened to help him much more carefully than they had Donna. She watched as three of them grasped him by the forearms and pulled him out. His blank stare unnerved Donna once again, and she averted her eyes.

Chaos had erupted around her. They were all speaking to each other anxiously, loudly, and rapidly, and it hurt Donna's ears, especially after the long silence. She just wanted them to shut up. But perhaps they were talking about the Doctor… perhaps they could help him.

She was pulled to her feet, and then the Doctor was next to her and she was being ushered forward, and she went willingly. She gave a sidelong glance to the Doctor, who she could now see more clearly than ever. Sweat was shining on his forehead, and he was obviously afraid. She saw that expression on him so rarely…

She slid her hand into his, and after a moment, he clutched it tightly as if it were a lifeline.