If you came all the way across the desert to see our famous cats, you might be disappointed. They're not actually green, but mottled in multiple shades: tortoiseshell and tabby, chocolate and calico. Only their eyes are green, bright as jade, like they know secrets. They might. Cats have been with us for thousands of years, since the dawn of civilisation. The truth is, they helped start civilisation, keeping vermin from storehouses of grain. The ancients buried them with honour in their pyramids, alongside their queens and kings.
They roam all over the desert, but most of them live in the desolate city. It's not really a city, but we don't know what else to call it. It sits in the middle of the desert, and no roads go there. It has great earthen walls on all four sides, and concrete towers at each of the four corners. It has strange curved buildings all through it, with no windows and no doors, and statues full of holes where the faces should be.
No one lives there, and I can't imagine anyone ever living there. By day, the black ground is baking hot from the sun. By night, the hollow statues howl when the wind blows through them. This is a place of silence and screams. The only good time to go is at dawn and dusk.
I live in the village, some distance from the city. It takes an hour to travel between them in my sandskimmer, rolling over the dunes, the sail billowing out in a good strong wind. I go there at least once a week, to visit the cats. I bring them little treats - a dried fish, the bones of a waterfowl, the heart of an ox. They sniff eagerly at my hands every time.
I watch them at play, and I make up little stories about their lives. Caesar finds a sunny new rock to conquer, but Cleopatra challenges him for it, and they both fall down in a tangle, and Constantine claims it instead. Naming cats is like naming stars - they don't care, and they don't answer. But it pleases me to have something to call them.
In life, they guarded the food of the people. In death, they guarded the tombs of kings. Sometimes, I wonder, what are the cats guarding now?
The strangers come from the sky, smoke blasting from their aircraft. They land outside the village, scraping a long furrow through the south field. People put down their sickles and baskets, to come stare at this sight.
The aircraft looks like a giant insect, with a gleaming black carapace and rainbow eyes. It shines like steel, more than I have ever seen in my life. It opens its throat and disgorges four people. They have come to see the desolate city. "We want a guide to take us there. We can pay." They bring out a glass vial shimmering with little flecks of metal: gold and silver, copper and iron.
Ulan, our elder, welcomes them. "Ally can show you. She practically lives there."
It's an exaggeration. I know well enough that the desolate city does not invite trespassers. Not exactly a forbidden place, but a forbidding place, full of signs that speak to the human heart: you are not welcome. But I've never been able to resist a challenge.
I look at the unsmiling strangers, and I don't feel trepidation. I feel a thrill. I guess that is my first mistake.
They say curiosity killed the cat.
They come from the northern mountains, and they are explorers of a sort. Vallo, Terl, Balt, and Carrock, who is leader of their expedition. He is the one who made their insect aircraft, and he owns a whole swarm of them, selling them to whoever can afford to pay.
Vallo tells me about other desolate cities that have been found all over the world. She has seen them with her own eyes. Some have great spikes of stone protruding from the earth, like thorns or teeth. Some are made from irregular cubes of concrete, with streets too narrow for more than one person. "It's as though whoever built them didn't want anyone to live there."
"Is that what you're looking for?" I ask. "Answers?"
Vallo gives me a mysterious smile. "Maybe. Or maybe buried treasure."
They walk into the desolate city with hushed awe. They look upon the earthen walls and the concrete towers, at the doorless buildings and the hollow statues. They look at the inscriptions that cover the walls of the city: letters in lost languages worn away by time, and carven faces distorted in pain and fear. There is no symmetry, no sense, only the same symbols repeated over and over.
The cats are engaged in their usual pursuits: sleeping in sunshine on top of the walls, hunting lizards that scuttle through the sands. But they come to investigate the strangers, slinking and stretching and purring. I pet them, but I don't have food for them today. They linger, hopeful, winding around my feet.
"A hundred years ago," Carrock says, "another expedition came to explore this city. Under the towers, they found rooms beneath rooms. What if they go all the way down?" He doesn't explain, down to where?
"They started to excavate a sealed stairway," Vallo says. "But they never finished."
An odd shiver runs down my spine.
Vallo notices. "What is it?"
"Just an old song," I say, reluctantly. I sing it for her:
The green cat says, 'Beware, beware!
Go no lower on the stair.
Run away when I am there.'
The green cat says, 'Beware, beware!'
"I'm not here for the cats, green or otherwise," Carrock says. "I'm here for the city. And what lies underneath."
We follow the stairs down, and the cats follow us.
Cats are hunters. But they are also survivors. They have lived on while other animals died out: lions and elephants, unicorns and dragons. They are unfazed by the harsh desert heat. They drink from salt lakes without ill effect. They hear in silence, they see in the dark. I am comforted by their presence.
Carrock and his people are prepared. They cut open walls with lasers and blast apart floors with explosives. We go down deep, through layers of rock, until we reach something incredible.
Caverns of salt crystal, pale salmon pink. A huge complex, almost as big as the city above. The cats lick at the salt pillars. They nose along the crevices. They scratch their claws along the walls, little puffs of pale powder spraying into the air. My lungs taste of salt.
The salt caverns are unlike anything I have ever seen. I never imagined something like this lay underneath our feet. The earth I knew seems like a fragile skin over the bottomless underworld. In stories, the underworld is the land of the dead, the house of shades, a hell: but it glitters in the light of our torches like a wonderland.
The walls of the caverns are translucent. Something lies in their depths. My first instinct is, don't disturb it. The scanner shows what they are: cylindrical objects, laid in rows. Vallo says the salt formations are slowly encroaching, and will eventually crush them all and bury them forever in the heart of the earth.
"Bring the drill," Carrock commands.
The drill is small enough to be hoisted into position by a single person. Its tip shines with diamonds. It shatters the salt into powder. Reverberations shake the caverns. The cats set up a caterwaul, the opposite of harmony. Everyone grimaces, except Carrock. He only looks intent. He knows what he is going to find.
A metal barrel, sealed shut. Like a coffin, like a sarcophagus. A threefold flower is imprinted on its surface: three triangular petals surrounding a circle in the centre. Carrock orders Terl and Balt to cut it open.
He lifts out metal vanes, glass cups, and plastic tubes. A strange collection of items. Why were these things buried here? And what happened to the people who made them?
"It doesn't matter what's inside," Carrock says. "It could be junk, for all I care. No, it's the containers. Metal. Barrels and barrels of it. More than you could imagine."
"There must be hundreds of them," I say, slowly.
Our world is metal poor. There is little of it in the ground where we can mine. Old relics corrode away with exposure to air. But these have been perfectly preserved in the salt all this time. A tempting treasure.
Then I see something that turns my heart to ice. The cats are glowing green. All of them, their fur luminous, and unmistakably green. They look unearthly, like they're stepped out of a ghost story. They regard each other with alarm, hackles raised.
The green cat says, 'Beware, beware...'
It's a warning. Not buried treasure. Buried poison. "We have to get out of here."
Carrock scoffs. "Are you afraid of superstitions? People used to believe seeing a black cat cross their path was bad luck. Do you see any danger here?"
I can't see anything dangerous. I can't smell anything dangerous. But I look at the cats, glowing that unnatural green, and I know they are sending a message to us. "I'm going. Now."
"Let's go," Vallo says. "Something's not right."
But Carrock turns his back. No one answers her.
The two of us flee up the stairs, back to the surface, surrounded by a flowing stream of cats. Once we emerge into the desert sun, the green glow fades. I wonder if I imagined it, but I look at Vallo and I know she saw it too.
We wait for the others, a night and a day, but they never come out. No one from the village is willing to go down there again. With the slow creep of time, the metal barrels and their poison will eventually be entombed, within walls of salmon pink salt. Perhaps new stories will be told, of the man who digs for treasure under the earth, trying to dig to the heart of the world, only for the green cats to stop him from waking a monster.
The desolate city is eroding, slowly scoured into dust by the desert winds. One day, its walls and towers will be gone and its foundations will be laid bare. Not in my lifetime, or my children's lifetime, or my grandchildren's lifetime. But someday.
In the central plaza of the city, there are two star maps. The constellations are the same, but the pole star does not match our own. The stargazers say, one map is from thousands of years ago, and the other map is for thousands of years from now. They say over time, even the heavens change their shapes.
One day, in the future, when the stars align, maybe the caverns will be ready to open. Maybe the cats will lead the way, showing us that it is safe, never again transforming into their green selves.
Until that day, they still keep watch over our treasures and our terrors: our eternal guardians.