As the creature’s attention settles, just for a moment, on his brother-in-law, Xiaodan turns on his heel and runs for his life.

He flees up the trail, sprinting through the mud as fast as he dares. Terror rushes through his mind like a river of freezing water, and what little conscious thought he can manage is mostly memories swept along on the flood. He can hear Zhong pleading with him, screaming stop, damn you, stop. He can hear the creature laughing, but it barely registers.

First there were messengers arriving at the capital in the spring, and the rumours that swept around the archives. It looks like war, people whispered to each other, and they nodded sagely because the signs had been there for months, with border skirmishes and angry sabre-rattling and ambassadors expelled, sent back in chains or worse.

Nobody took it very seriously. Who were the Zhǎiguān army, to think they actually stood a chance? The northern kingdom was poor, landlocked, and forever borrowing from its neighbours, Mùrén most of all. An invasion? It was like a layabout son threatening to “invade” his parents’ house.

Xiaodan slips on a thick mat of dead leaves and almost goes down on his face. His left hand sinks in the mud. The effort to stop himself from falling makes the arm throb with pain. He picks himself up and continues running, veering from side to side like a drunken pickpocket trying to outrun the constables. His pulse hammers in his ears.

“Are you serious?” Xiaodan looked up.

”Very,” Cai Peizhi said quietly.

Xiaodan blinked, but the old man refused to smile. His face was like a wrinkled apple beneath his towering hat.

“But these are stories.” Xiaodan tapped the scroll. “Begging your pardon, sir. Still. The Yèkǒng? The Night Terrors? You want someone to search the street markets, not the records. Maybe a puppet show would –”

“The reports were very clear.” The archivist toyed with the end of his long white beard. “They’re fighting side by side with the Zhǎiguān rank and file. Taking orders. They’re…”

The silence was so great they could hear the clerks scribbling furiously on the floor below.

“They’re formidable opponents,” the old man said at last.

The seal glistened at the bottom of the message; the governor’s stamp, a snarling temple guardian, the ink still damp.

“I’m not sure I’m up to this.” Xiaodan swallowed. “Sir. Matters of national security, I mean.”

“I disagree,” Cai Peizhi said. He smiled, then, the slightest curve of his aged mouth. The expression struck Xiaodan as oddly sad. “I know you never saw this as your calling. But you’re very good at it, whether or not you wanted to work here. Unearthing secrets, I mean. As good as anyone to whom I’ve told this news.”

The praise was unexpected. The senior archivists all seemed to feel compliments encouraged the younger members of staff to let their deadlines slide.

“Which is what we need, you see?” And Xiaodan realised, in that moment, that the old man wasn’t so much wistful as terrified; so frightened he couldn’t stop himself from talking. “Because without those secrets being dug up, boy – if we can’t find some weakness these things possess –”

The trees are thinning out. There’s nothing here, boy! Zhong had shouted, but obviously he was wrong. A pair of giant wooden gates twice his height stand across the trail. They’re black and rotten, now, with one long since fallen over, and the other halfway there. Xiaodan vaults up onto the fallen gate, staggers down the sagging timbers and through the entrance.

He can hear Zhong weeping, somewhere behind him, like a ghost condemned to haunt the mountainside. Dimly Xiaodan wonders why the Yèkǒng hasn’t caught up with the other man yet.

As the weeks dragged on, the war drew closer, and nothing Mùrén could do was enough to hold it back, but the stories still seemed too fanciful to be believed. The rumours spread beyond the court, but the authorities insisted everything was fine, right up until the Zhǎiguān armies were massed outside Gāozhū with the Yèkǒng in tow.

Military superiority counted for much less against these things. They surged over the city’s defences. They could bring down ten opponents without breaking a sweat. They were lighter and quicker on their feet than a human being, and stronger, too. The only way to put a Yèkǒng down for good was to take its head off.

Even then it might still gut you with one last swipe of its claws. And if you left them an opening, there was the scream. They could howl loud enough to send a grown man reeling with blood streaming from his ears, or if he was up close, to drop him on the spot.

So Mùrén’s capital city fell, and for some time afterwards it was chaos in the streets.

River of Heaven. The sign lies half-buried in the long grass. Some noble who thought he’d impress the governor by giving his landholdings a flowery title after he’d struck it rich. Once upon a time the mine must have brought up cartloads of ore, day after day. Xiaodan can see warehouses, cranes overhead, dormitories big enough for several hundred workers…

All ruins now. The rooftops have fallen in, the cranes collapsed. Ivy is strangling what’s left. The innkeeper wasn’t lying. Looters have carried off everything, and even started on the bricks. Xiaodan stumbles through the streets. His leg hurts where he fell, running up the trail. The knee throbs, as if he’s sprained it.

“What are you doing?” Zhong whispered.

There were no lights in Lam Ka Ho’s offices at this time of night, but you still had to be quiet. People said the Yèkǒng patrolled the rooftops after dark, looking for the last pockets of resistance as the Zhǎiguān troops tightened their grip on the city. Only Tsang Wai Yi’s name had persuaded the merchant to let Xiaodan use it as a hiding place.

“Leaving,” Xiaodan said. “The day after tomorrow. Before sunrise.”

“Are you insane?” Zhong gaped at him. “They’ve got her under house arrest, you realise. Doesn’t that mean anything to you?”

“I heard.” Xiaodan nodded. “My parents were picked up as well –”

“Well, yes.” Zhong waved one hand in dismissal. “But… you’re running away –?” He took a step forward, raising his fists. “You can’t. You can’t!”

“I found something.” Xiaodan tried to keep his voice level. Zhaoling would be none too impressed if he had to break her oldest brother’s arm, or worse. Even less so if they were both arrested in the process. “Just before they took the archives.”

He’d heard them all by that point. Don’t tell me you believe this? How much did you pay for it? Or that old favourite, so what does it really mean?

But Zhong only looked at him with a curious expression on his face, part bafflement, part simmering frustration.

“Show me,” he said.

Xiaodan turns a full circle, trying to work out where the minehead might be. The motion leaves him nauseous and dizzy, after butting heads with that poor Zhǎiguān soldier. He can see the mountainside looming over the mining complex, but many of the ancient walls between the ruins are still standing, and he doesn’t have the strength to climb over them.

Zhong is still screaming weakly in the distance.

Wheel ruts in the mud, deep enough the undergrowth and the falling leaves haven’t covered them entirely. Xiaodan stumbles along the tracks. He’s so exhausted his legs feel as if he’s walking on stilts.

A shriek from Zhong. Another, and Xiaodan realises what the Yèkǒng is doing. It’s toying with them.

But he can see the minehead at the other end of the street.

“Silver,” the innkeeper said. “But that was a long time ago. You’re not thinking you’ll find anything still there? Looters carried off the last of it, back when I stood about as high as my father’s knee.”

“Nobody stopped them?” Xiaodan asked. He put a hand to his satchel, and felt the comforting weight of his sword inside.

“Fellow what owned the mine was supposed to send soldiers to stand guard, or so I heard.” The innkeeper snorted. “Mind you, he couldn’t pay the taxes, let alone their wages, and then people started seeing ghosts up there, and –” A shrug. “But anything valuable, well.”

“It’s nothing anyone could sell,” Xiaodan said quickly. He tried to ignore Zhong visibly rolling his eyes at the other end of the bar.

“If you say so.” The innkeeper lifted a tray; a jug of wine, skewers of chicken, a fly drawn by the smell. “If you’ll excuse me, friends. Duty calls, even with the war on… but it’s right there, eh? Up the mountain path, where the carts used to come down. Tiāntáng Zhī Hé, that was the name. Take a look for yourselves. Nobody’ll stop you.”

The cart tracks lead to double doors in the cliff face, wider and taller than the village gates. One of them is open, darkness inside. It’s starting to rain, spitting fitfully as the wind picks up. Xiaodan staggers towards the entrance, sobbing for breath. He turns, just outside the doors, and realises in horror that Zhong is rounding the corner, some distance behind him.

So behind Zhong, then –

Xiaodan breaks into a sprint. Almost immediately he trips, rolling in the mud. He lands badly on his left arm and screams; struggles to his feet and from somewhere manages a last burst of internal energy that carries him over the threshold into the shadows.

He stumbles to a halt, wheels round and hurls his full weight feebly against the door. Zhong sees him, realises what he’s doing and shrieks again, tottering closer. He hasn’t got the strength to form words. Xiaodan pushes furiously, weeping with rage. His left arm feels as if it could snap like a twig at any moment.

The door shifts. An inch. Two. A foot, and then suddenly it’s grinding across the floor. Zhong is running, now, fresh blood staining the makeshift bandage around his calf, but he’s too slow. The door shuts with a tremendous echoing crash. Xiaodan fumbles in the half-light for the heavy iron bolt, slams it into place and brings it down.

He sinks into a crouch with his back against the wood, hugging his knees as the rain begins to come down harder, while Zhong continues howling, trapped on the wrong side of the door.