The Blood Engine

The air at the foot of the basalt stairs did not carry the stench of the upper sumps. It smelled of pulverized granite, cold copper slag, and dry river mud that had not seen sunlight in five hundred years.

Nduoma kept her right hand clamped around Chidalu’s upper arm, counting each riser as her worn sandals met the edge. Eighty-four steps down from the unsealed well-head. Her left wrist, bound in stiff hemp after the collapse at the Five-Arch Confluence, throbbed with a dull, rhythmic ache every time her heel struck stone. Her right palm, scorched dry and clean by the heat of the obsidian sigil, felt stiff, the skin pulled tight across her lifeline like cured parchment.

"Ndu," Chidalu whispered. His voice was raw from the kiln flues, thin as dried grass. "Where does this go? This isn't under the Tanneries. There aren't any drain flues here."

"Quiet," she murmured, scanning the darkness ahead. "Watch the tread. The stone isn't dressed with mortar. It’s dry-stacked ashlar."

She ran her bare fingertips along the left wall. The jointing was seamless—granite blocks three spans wide, fitted so tight that even a sliver of ox bone could not find purchase between them. In the city above, every foundation wall was patched with wet gray lime, constantly weeping silt under the tread of the night patrols. Here, the stone was bone-dry. The pressure of the earth above ought to have crushed an unmortared hall of this breadth, yet the ceiling arched upward into an immense, ribbed barrel vault that swallowed the faint, smoky glow of her tallow dip.

They stepped off the final riser onto a floor of dark flagstones laid in concentric circles.

The chamber was circular, easily eighty paces across. Eight colossal octagonal pillars of dense black basalt rose from the perimeter, canted inward at a subtle, deliberate angle to distribute the immense weight of the bedrock above. But between the pillars, suspended five feet above the flagged pavement by thick verdigris-crusted bronze chains, hung something that made Chidalu stumble into her hip.

Figures.

There were twelve of them, spaced evenly around the perimeter ring. They were human in form, yet their proportions were elongated—long, thin limbs and ribcages expanded like hollow wicker baskets. Their skin was not gray and sloughing like the conscripted corpses marched onto the perimeter ramparts every dusk. It was the color of smoked cedar, pulled tight over bone, completely devoid of rot. Heavy bronze collars encircled their throats, each collar pinned directly into the stone pillars behind them by square iron drift-bolts. Long bronze needles, thick as a carpenter’s awl, were driven through their collarbones and forearms, linked to thin, braided copper wire that ran down their dangling legs and disappeared into narrow channels cut directly into the flagstones.

Chidalu shrank back against her side, his breath catching in his throat. "Are they... are they the first line? Did the arbiters hang deserters down here?"

"Deserters rot," Nduoma said under her breath, her eyes tracking the run of the copper wire along the floor. "And corpses don't keep their joints pinned under tension. Look at the wrists."

The figures were motionless, their eyes closed, their jaws slack. Yet their dry chests did not collapse inward. Beneath the parchment skin of their throats, a faint, sluggish pulse stirred once every ten heartbeats—a slow, mechanical spasm that tugged against the bronze needles pinned through their flesh.

"They're alive," Chidalu breathed, horror bleeding through his dry voice. "Ndu, they're still breathing."

"Barely," she said. Her mind worked automatically, stripping away the terror to read the load and purpose of the masonry. "They aren't prisoners. They're anchors."

She followed the copper channels toward the center of the hall.

In the middle of the concentric circle, the floor dropped away into a massive, octagonal pit twenty paces wide. Suspended directly over the yawning abyss was a colossal machine of dark slate and interlocking red copper plates, shaped like an inverted, multi-tiered beehive. It hung from four massive iron stay-chains anchored into the vaulted ceiling. Thick lead siphons, each the width of a man's torso, plunged down from the shadows of the high roof into the machine's crown.

A low, subterranean hum vibrated through the flagstones, rising through the soles of Nduoma’s sandals and rattling in the teeth of her lower jaw. The vibration carried no friction of grinding earth or iron-ward rattle, but the heavy, rhythmic thud of fluid moving under immense hydraulic pressure.

Thump. Thump. Shhh-clack.

Nduoma approached the edge of the octagonal pit, keeping her footing steady. She held her tallow candle over the void.

The siphons did not come from the outer walls.

She stared up into the darkness above the machine, tracing the trajectory of the massive lead conduits. Two of the main intake trunks ran straight north-northwest, rising at a forty-degree angle directly toward the Upper Spire reservoirs and the high houses of the Arbiters. The other four trunks converged from the east, directly beneath the drainage sumps of the Eastern Basin collection pens—the very cradles where Master Okoye’s weavers and her brother were supposed to have been drained tonight.

"By the foundation," Nduoma muttered, her fingers tightening into a fist.

"What is it?" Chidalu asked, creeping to her shoulder, keeping his eyes carefully averted from the suspended figures along the perimeter.

"The blood," she said. Her voice was flat, hard as a chipped wedge. "Overseer Obioma told the entire district that the perimeter walls were failing because the lower kilns were short five hogsheads of fluid. He doubled the tithe to forty obols. He told us the dead on the border ramparts were starving."

She pointed with the brass casing of her tallow candle toward the distributor hub at the center of the slate hive.

Transparent conduits of thick, green-tinted volcanic glass bridged the copper valves. Inside them, dark, thick crimson fluid pulsed in sluggish, measured surges. Every three seconds, a valve slammed shut with a muffled metallic clack, driving a measured volume of fresh blood down into the core of the machine. From the base of the machine, a single, massive copper conduit plunged straight down into the pitch-black chasm below.

"It isn't going to the walls," Chidalu said, his eyes widening as he followed her pointing hand. "None of it is going to the outer gates."

"Not a drop," Nduoma said. "The outer ring pylons are running dry because every hogshead extracted from the Eastern Basin is piped straight down into this sump. The entire city’s collection grid is pitched downward. It’s an inverted siphon."

"Why?" Chidalu grabbed her sleeve with trembling fingers. "If the wall wards fail, the ash-wastes will spill into the streets. The wild dead will tear the lower wards apart. Why would the Arbiters starve their own soldiers?"

"Because the soldiers on the wall aren't what they're afraid of," Nduoma answered.