The first thing Mihao knew was sand. It was in his ears, in his eyebrows, and most of all in his beard, which was long and white and very much his own, though he could not have told you how he came by it.

The second thing he knew was the sky: purple, enormous, and empty of names. The third was the book lying open beside him. Every page was blank except the first, where someone had written, in a hand he almost recognised: Once upon a hao.

He tried, of course, to read the rest. He turned the pages forwards and backwards, held them up to the moon, sniffed them, and once, in a moment he was not proud of, licked one. The book stayed politely blank.

Yet it was warm, the way a sleeping animal is warm, and when Mihao touched the four words they shone gold. So did his beard. A single white strand lifted on no wind at all and pointed east, towards the pyramids. Hao, he thought. In a tongue he no longer spoke, it meant a thing that has been told. And Mi-hao meant the one who keeps them.

On the third day a caravan found him: twelve veiled travellers and their long-legged dune-beetles, each beetle loaded with jars of salt and bundles wrapped in cloth. The Saltwalkers traded in salt by day and in names by night, for in the desert a name was the only thing that did not blow away.

Their leader was a woman called Hadda, small and sharp and older than she looked. She studied Mihao’s beard for a long while. “You are not from here,” she said at last. “Nothing with that much memory in it is from here.”

That night, by a fire of thornwood, Hadda poured a little sand into Mihao’s paw and told him to look closely. Each grain was a tiny, worn-down letter. An a. Half of a w. Something that had once been a full stop.

“This desert was a country once,” she said. “Rivers, cities, a king who kept bees. Then the stories about it stopped being told, and the Hollow came and ate what was left. This is what a forgotten place looks like, Grandfather.” She let the letters run through her fingers. “Somewhere there is a library that remembers everything. My grandmother said it broke. She said it broke into nine pieces.”

Near midnight the stars above the camp went out one by one, as if someone were pinching candles. Where they had been was not darkness but a pale, papery nothing. Hadda called for her grandson, then stopped, puzzled. She could not remember his name.

Mihao stood. His beard blazed gold, the blankness flinched, and the stars came back. In his book, beneath the first line, new words were drying: Go down, beneath the pyramids, where the kings kept their names.