Wei Zongyuan did not release his saber. Before him sat no frightened exile, but an instrument that could chart the ruin of an empire from one charred splinter.
“The penal pits,” Yutang said, her voice flat. “They are a death trap. A fresh collapse is inevitable without reinforcement. We need fired limestone, silicates, and clay. Not for mortar, but for pozzolanic binder.”
Wei raised an eyebrow. “Binder? A formula considered lost to the Elder Dynasties? You propose to revive it from dust?”
“Not revive,” Yutang corrected, her gaze already sweeping the rough-hewn timbers above, calculating angles. “Reverse-engineer. The old records describe the mortar, yet omit kiln conditions. The proportions are evident. Limestone from the upper ridge, red clay deposits along the creek bed, and washed river grit. The ovens are already set for ore smelting; we need only alter the firing heat and lime ratios.”
Wei studied her face. “And what purpose would this binder serve in an extraction pit?”
“To seal fractured cliff faces,” Yutang stated, turning toward him. “To form an impermeable barrier against water ingress. To erect retaining barriers and spillways that will withstand flash floods. To make these slopes defensible.” Her tone stayed level. “My family’s name requires a foundation stronger than rumor, Commander. It requires cured aggregate.”
He gave a slow nod. “So it does. Very well. Raw materials will be delivered. The prisoners are yours to command, within the bounds of productivity. But do not forget the true objective, Lady Shen.”
“The Qixing gallery,” she said. “I have not forgotten. But I require more records.”
Three days later, a rough-spun sack, far too heavy for its innocuous appearance, appeared outside Yutang’s hut. Inside, tightly rolled and sealed in oiled silk, lay drafting rolls of the Qixing terrace. The parchment cracked along its creases, inked in the exact lines of Master Builder Li Feng, who had died during the catastrophe. The sheets smelled of dry cedar and damp cellarage.
Yutang spread the voluminous schematics across her makeshift table. Elevations, cross-sections, and mortise diagrams covered the wood, lit by a single tallow wick. The night settled into the dry friction of drafting parchment and the scrape of her charcoal marker.
Wei Zongyuan entered without knocking. He often did, a silent shadow materializing in the doorway, observing her for long minutes before speaking. Tonight, he placed a small, lacquered box on the boards between them. “From the Imperial Archives. Not drafts, but the supply ledger for the site. Mismatched sums might show intent.”
Yutang barely glanced up. As she pulled the ledger forward, her knuckles brushed his cuff, the rough dyed silk raspy against her knuckles before she opened the register.
“These columns,” she murmured, running an index finger across the second-tier load lines. “They carried safety margins thrice their dead weight. Even with pre-cut tenons and vinegar rot, a single shear should only cause local sagging. Total framing collapse during the procession demands a cyclic stressor.”
She took a flat river stone and tapped the drafting paper. “A harmonic pulse. Not a singular hammer drop, but continuous frequency matching the timber’s natural oscillation.” She tapped again, setting a rigid interval. “A forced cadence.”
Wei’s eyes narrowed. “A cadence? You mean… marching?”
“Exactly,” Yutang said. “Ceremonial infantry. Synchronized boots striking at the span’s resonant period would magnify deflection twentyfold until the tenons snapped. The palace guard keeps a rigid pace: fifty paces a minute in formal armor. If their path crossed the compromised crossbeam while the chemical wash dissolved the core…”
Across the excavation cuts, the labor gangs adjusted to her yardsticks. Work crews hauled calcined rock from the upper bluff, fractured it with iron mauls, and fed the blast kilns. Alkaline ash hung thick over the trenches. Her first batches of hydraulic lime yielded a dense, fast-curing paste. They mortared fissures, braced hanging boulders, and braided oiled hemp into barrier mesh anchored into rock face bolt holes.
“The hemp grid takes falling scree,” Yutang instructed the labor leader, Jia. “Distribute the dead load through the pinned iron brackets. Check the guy-wire tension. The lowest row must absorb maximum kinetic force.”
Jia spat in the dust and shouted her directives along the trench.
At midday, while she checked anchor depth along the lower escarpment, a crack split the cliff rim. Shadows swept down the wall. Three limestone boulders dropped straight toward the tier where she stood, levered free from an overhead shelf.
Iron brackets screeched as the first block took the hemp netting. Strands groaned under dynamic impact, stretching four paces before arresting the mass. The remaining stones struck the lower weave, trapped midair above her head.
On the terrace ten paces above, a laborer dropped his iron pry bar. His mouth hung open, eyes pinned to the swinging mesh rather than the rockfall below. Yutang stepped from beneath the loaded cables, brushing chalk dust from her sleeves, and met the man’s stare. Across the terrace, Wei Zongyuan emerged from behind an ore cart, draw-knife in hand, stepping soundlessly toward the saboteur.