A Chitin Dagger

Steam rose through the floor slits with the smell of boiled horn and curdled tallow.

Xie Yunshan adjusted the strap of his tool sling, his fingers checking the edge of his sapper pick. The bronze tip had flattened against an iron-banded conduit an hour earlier, leaving him with three inches of blunt wedge where he needed a chisel point. If another blind crawler dropped from the vault ribs, hitting it with dull bronze would only ring its shell like a temple chime. He needed edge-steel, or something hard enough to bite into segmented hide without bending.

"The nursery flue," Bai Tingxu said, pointing his tallow flare toward a low arched passage where the brickwork was slick with yellow grease. "When the sub-terrene broods swell past their third instar, the old casing binds their breathing spiracles. They crawl into the heat-draft to bake the shell dry until it fractures along the spine."

Tan Fenglan kept her posture upright despite the four-foot clearance of the tunnel roof. Her silk-bordered coat was smeared with dried ox gore, but her hand rested firmly on her bent sounding rod, using it as a cane against the greasy incline. "The Conservator logs note twenty baskets of scrapings taken from these flues each spring. The mortar masters grind it to seal the granary base against groundwater."

"The mortar masters were scraping dead husks," Tingxu replied, smoothing the stiff hemp of his blood-stained butcher apron as he stepped over a puddle of warm, viscous brine. "We need plates from a live shed. Once the casing cools without grease, it turns brittle as dry river mud."

Yunshan crouched at the mouth of the chamber. The air was five degrees hotter here, heavy with moisture that tasted of mineral salt and ammonia. Across the center of the low brick dome lay the cast-off carapace of an earth-leech. It measured four paces from the ragged cephalic cowl to the split caudal taper, translucent as oiled parchment at the flank but thickening to a thumb's depth of black, ribbed plate along the dorsal ridge.

"A juvenile," Yunshan remarked, prodding the outer rim with his boot. "Scarcely broad enough to swallow an ox whole."

"A juvenile that shed its hide six hours ago," Tingxu said. He drew a notched butcher's cleaver from the leather wrap at his waist. "The imperial rite requires prayers of appeasement before the harvest. We offer the beast thanks for its sheath."

"Pray to your own boots if it keeps them moving," Yunshan said. He knelt beside the split dorsal seam, running his thumb along the fracture line. "Out on the salt steppe, when we find a dead camel, we skin the ribs first and talk to the sky when our bellies are full. Hand me the copper wedges."

Fenglan pulled two flat wedges from her surveyor pouch and passed them down. "Strike along the lateral suture. The grain of the chitin runs diagonally toward the spiracle ports."

Yunshan did not answer. He leaned close to the shell, tapping the black plate with the poll of his bronze hammer. The sound was high and sharp, like struck slate. He located three fine stress veins radiating from the primary split—fault lines formed when the beast had flexed its musculature to tear free.

Setting the first copper wedge two finger-widths off the center groove, Yunshan tapped it twice to seat the blade, then drove a single heavy blow into the bronze butt.

The plate gave an acoustic snap. A foot-long blade of dense, black horn peeled away from the fibrous inner skin. Yunshan caught it before it hit the floor bricks. The material was warm, surprisingly light, and carried a natural bevel along the fracture that ended in a taper sharper than flint.

"Look at the under-casing," Fenglan whispered, stepping closer with her torch.

Yunshan flipped the shard. Embedded in the hardened amber residue of the inner lining were hundreds of intact barley hulls, calcified directly into the tissue of the molt.

"They are not just digesting the grain," Yunshan said, tracing the yellow husks with his nail. "They are building their bones out of your winter harvest."

"The sacred diet was ox blood," Tingxu murmured, staring at the embedded chaff. His fingers tightened on his cleaver. "Five centuries of steer blood through the bronze pipes kept their hides thin and pliable. Without the blood, their humors turn dry. The starch binds in the gut. The casing hardens twice as thick."

"Which means your garrison won't pierce them with standard bronze spearheads," Yunshan said.

He worked the copper wedge into the next fissure. He struck with measured rhythm, letting the leverage of the tool follow the natural grain rather than forcing the cut. Three more strikes yielded two heavy, leaf-shaped daggers and a broader, curved slab with a serrated margin that could serve as a trenching spade. He wrapped the hilts in strips of hemp cord torn from his tool bag, binding them tight until the rough chitin stopped biting into his palms.

He tossed one of the daggers toward Tingxu, who caught the hemp wrap with a practiced hand. He handed the second to Fenglan.

The Conservator inspected the dark blade, turning it beneath the torchlight. "A primitive instrument for a granary officer."

"It cuts," Yunshan said, sliding his own blade into the loop of his belt. "And when the floor gives way again, a primitive edge in your hand is worth more than a library of imperial ledgers."

A faint tremor ran through the mudbrick floor, so subtle it registered first as a ripple across the brine pools.

Tingxu froze, his head tilted toward the low ceiling. "The scent."

"What scent?" Yunshan asked, wiping grease from his knuckles.

"Fresh molt smells of musk and bile to us," Tingxu said quietly. "To the broods in the deep drifts, it smells like an unarmored sibling. A soft meal."

From deep within the bedrock beneath their boots came a sound that had nothing to do with falling stone or wind in the flues. It was a rhythmic, concussive hydraulic thud—slow, methodical, and heavy enough to vibrate the iron pins in their boot soles.

Thump. Thump. Thump.

Fenglan laid the flat of her palm against the chamber wall. The mortar between the bricks wept a fine drizzle of dust.

"The cadence is four times slower than the juveniles," Fenglan said, her fingertips feeling the pulse through the brickwork. "The displacement is fifty spans long, but it is not climbing toward the flues. It is tracking the main weight column beneath the central chute."

"The grain bins," Yunshan said.

"The third tier supports," she replied, withdrawing her hand. Her fingers were coated in grey limestone flour shaken loose from the joint mortar. "If the creature shears the southern timber array, the weight of the middle vaults will drop eighty cubits into the mud. The whole silo will fold inward upon itself."

Yunshan looked down at the hollow carapace resting in the center of the dome, dark and ridged like an upturned boat. The tallow flare guttered in the descending draft, casting long, still ribs of shadow across the salt-filmed floor. They could not hold the foundation from the dark of the drain flues. He cinched the canvas strap over his shoulder, turned his back on the abandoned husk, and pointed his chisel toward the upward vent shaft.