The moon was already disappearing behind another veil of cloud and the chamber was darkening again.
Daniel lurched forward and managed to sit up, his cold arms like stumps because he could no longer feel his hands. When he wobbled forward and slid down on to the shoreline, his knees clicked and his arms flailed as he tried to stand up. But he was too weak to keep his balance.
In the last dregs of moonlight, he plotted a route over the pale, rocky rim round the water.
And then it went dark.
He crawled painfully through the pitch-black, from stone to stone, until he bumped against the rock wall of the chamber and began to follow its slow curve round. The dark tried to spin him about, but he kept going, the noise of the waterfall a pivot around which to crawl.
A couple of times he thought he had found the tunnel and then had to backtrack when he discovered a dead end. But, eventually, he found a wider opening and he kept crawling forward, battling up the gradual slope, the waterfall becoming quieter and quieter, his breathing louder. He collapsed on his front from time to time, crying out as he hit the rocks, so cold it felt like bone on bone.
He stopped, frightened, when he heard a different sound above him until he realized what it was: the hiss of leaves in a breeze.
When his hands touched a fringe of silky grass, he gasped and lay on the ground at the mouth of the hole to try and gather more strength.
There were woods to his right.
In front of him was a large meadow, like a sheet of black ice without the moon to light it.
The night was dark. But it was a dark he knew by smell and sound. It was a dark that warmed him.