The chemical stench of rotting vegetation and packed burning acid drifted three leagues across the Black Fen.
Along the southern drainage levee, forty yards of the new strap-iron tramway lay numbed beneath a creeping carpet of velvet-black mold.
The fungal mats didn’t grow like ordinary swamp moss.
They pulsated with a slow, sickening rhythm, swelling into glossy black pustules that cried pale yellow acid directly onto the iron strap plates.
Where the acid touched the metal, cold-rolled forged iron dissolved into orange flakes of spongy rust with a steady, poisonous hiss.
Giles Croft stood on the unaffected ballast ten paces back. He held a brass test spatula and a battery of three stoppered glass phials.
He scraped a thick smear of the black slime from an oak sleeper, transferring it to a fine china reaction dish.
“Acidithiobacillus-type anaerobic fungal secretion,” Giles reported, adjusting his tinted glasses against the sour fumes. “The organism metabolizes inorganic sulfur and ferric ions present in the bog water, producing packed sulfuric acid and oxalic chelating agents.
The pH is about two point one. It’s a textbook microbial-induced rusting vector.”
Rook Red-Mane crouched on the ballast beside Kenneth Drake, his notched bone tracking vane twitching in his hand.
“It’s Hesketh’s marrow-moss,” Rook whispered, his amber eyes fixed on the weeping mist of the southern marsh. “Hesketh the Rot-Weaver sits in the Sunken Sump upon a throne of dead trees.
He has three hundred cultists chanting in the muck, and they feed their blood to the Black Mildew. Whatever their shadow touches turns to liquid rot.”
“Fungus can’t eat stone, and it can’t eat a bitter-salt barrier,” Giles said. He closed his test chemical kit.
“The organism needs an acidic substrate between pH two and four to maintain body-energy enzyme function. If we spike the soil pH to twelve, the cellular membranes saponify and the mycelium undergoes instant osmotic lysis.”
Rook blinked, his wild red hair bristling. “Osmotic... What?”
“It pops,” Giles said simply. “Like an over-inflated bladder. Sister Teresa, deploy the sanitation battery.”
Sister Teresa of the Pure Cistern stepped forward onto the ballast bed like a general commanding a siege train.
Behind her rumbled a four-wheeled timber wagon carrying a five-hundred-gallon iron tank lagged in thick felt, bubbling and hissing with violent internal heat.
A hand-cranked copper shifted weight pump, driven by two sweating hospital new students, kept the tank high-pressure to sixty pounds of pressure.
“The plague of the unwashed mire,” Teresa declared, her wimple straight as a carpenter’s rule, her fingers tightening on the dual-grip handles of a six-foot brass lance nozzle. “They dare touch the clean rails of industry with their rotting slime!
New students, pump the air! Bring the pressure to sixty pounds!”
The new students threw their full weight onto the wooden pump-beam: thump-hiss, thump-hiss.
Inside the lagged tank, fifty bushels of unslaked calcium oxide lumps were reacting with boiling water, generating an exothermic slurry of fresh burning lime powder at nearly two hundred degrees Fahrenheit.
Inside the lagged tank, the chemical reaction was reaching its peak.
Sister Teresa checked the heat with a long copper dip-rod, sniffing the rising steam with practiced familiarity.
“Three hundred degrees in the core,” Teresa reported, her hand steady on the valve. “The lime is slaking true.
When water touches unslaked rock, the heat born within the stone is fierce enough to boil mutton. It’s the wrath of the pure earth let loose upon corruption.”
“It’s the exothermic enthalpy of hydration,” Giles corrected, adjusting the relief valve on the tank dome. “Calcium oxide reacts with water to form calcium hydroxide, releasing sixty-three point seven kilojoules per mole of reactant.
The resulting bitter-salt slurry has a pH of twelve point four, which saponifies fatty acids and denatures bacterial and fungal proteins within seconds. Wear your leather gloves, Teresa. Calcium hydroxide is severely acid-burning to human eye tissue and outer skin.”
Teresa adjusted her heavy leather mittens with a grim nod. “The righteous don’t fear the sting of the cleanser, Lord Master builder.”
Teresa stepped onto the edge of the fungal mat, planted her boots firmly on the ballast. Then she opened the master discharge valve.
ROOOOOOAR.
A scalding, high-pressure jet of boiling, milky-white burning lime powder slurry erupted from the brass nozzle with the force of a clouded eye.
The skin-burning jet slammed into the pulsating black mildew.
The reaction was immediate, violent, and spectacular.
The boiling bitter-salt chemical struck the acidic fungal mats. Then, an intense acid-base neutralization reaction blew up across the railway bed.
Clouds of scalding white steam shot twenty feet into the chill morning air. It hissed like a hundred angry vipers.
The black velvet mats didn’t merely wash away.
Under the ferocious heat attack and extreme pH twelve alkalinity, the fungal cell walls burst instantly.
The black pustules shriveled, blackened. Then he dissolved into grey, inert ash that washed harmlessly down the crushed granite ballast into the drainage ditch.
Teresa swept the brass lance in wide, disciplined arcs, laughing with fierce, void-court delight.
“Burn, foul rot!” Teresa cried, her voice ringing over the hissing steam. “Taste the scouring salt of the living water tank! Cleansed by fire and washed in lime, the earth belongs to the pure!”
Kenneth Drake leaned on his pacing rod. He watched the boiling white foam devour thirty yards of black corruption in less than four minutes.
“Remind me never to insult the Sister’s laundry,” Kenneth muttered under his breath.
“A sixty-pound burning lime powder spray at ninety degrees will remove eighty percent of all organic contaminants within ninety seconds,” Giles noted, checking his watch.
“It’s the standard town disinfectant protocol for plague zones and open slaughterhouses.”
Toby Karr and a squad of twenty laborers followed close behind the steam cloud, equipped with iron rakes and wooden tamping bars.
They shoveled fresh, sharp-edged dark rock ballast into the cleared trench, lifting the sunken ties with track jacks and tamping the stone firm.
Master Borin Bronze-Lung followed with replacement strap plates. His smiths driving was heavy countersunk spikes into the sound oak beneath.
Within forty minutes, the forty-yard breach had been sterilized, re-ballasted, and re-tracked.
CLACK.
The check handcar rolled smoothly over the newly repaired section without a fraction of an inch of settlement.
* * *
By mid-afternoon, the sanitation crews had pushed two hundred paces into the margin of the marsh, following Rook Red-Mane’s tracking vane.
Hidden within a dense grove of weeping willows, they discovered the source of the living sabotage.
It was a crude, horrifying altar built of blackened willow trunks bound with human sinew, crowned with a rotting stag skull wrapped in pulsating black fungus.
Three wooden vats stood beneath the altar, filled with fermenting marsh slime, dead carp, and copper sulfate crystals, actively bubbling with acidic spores.
“A spore shrine,” Rook whispered, his bow drawn and notched with a broadhead arrow. “Hesketh uses these to seed the wind when the north breeze blows.”
“It’s a stuffy open-vat fermentation pit,” Giles said, stepping forward with his clipboard. “Running in direct rule-break of town sanitary zoning ordinances. Teresa, stop the vats.”
Teresa stepped up with her lance.
Two blasts of boiling burning lime powder slurry filled the wooden tubs. The fermenting black broth wildly curdled, boiling into harmless grey curd that ceased to bubble within twenty seconds.
Duncan Stone-Splitter stepped forward with his twelve-pound sledgehammer and shattered the wooden altar into kindling with three massive blows.
“That’s three shrines destroyed today,” Kenneth Drake reported, walking the outer edge with his scouts. “The air is clearing, my lord. The wind no longer smells of vinegar.”
Lady Millicent Croft walked along the cleared ballast, her tally-book open and her brass nib moving rapidly across the ruled parchment.
“That single decontamination run burned up forty bushels of high-calcium burning lime powder,” Millicent noted. He looked up with her sharp, calculating gaze.
“And two drums of refined copper sulfate from the Under-Pass stores. If we must wash two miles of track every week to keep Hesketh’s mold from eating our oak ties, Giles, our sanitary waste will exceed the cost of our grain rations.”
“Preventative sanitation is always cheaper than capital replacement,” Giles replied calmly. “Replacing two miles of rotted oak stringers and sixty tons of rusted through strap iron would cost four hundred silver sovereigns and need three months of downtime.
A weekly burning lime powder wash costs four shillings in raw limestone and forty man-hours of apprentice labor. The return on investment is nearly eight hundred percent.”
Millicent paused, recalculating the figures in the margin of her ledger. A slow, dry smile touched her lips.
“Very well,” Millicent conceded. “I’ll allocate eighty bushels of lime per month under the town pest-control account.”
“We must establish permanent prophylactic spray stations,” Giles directed, sketching a diagram on his pad. “Toby, build three raised timber towers along the levee hall, each fitted with a gravity-fed tank of five percent copper-sulfate wash.
Keep the vegetation along the right-of-way sprayed weekly. Preventative upkeep is ninety percent of pest control.”
“Right away, Lord Giles!” Toby said, rolling his chalk-reel.
Before Toby could turn back toward the tracks, the ground beneath their boots shuddered.
It wasn’t the sharp, metal shaking of the pile-driver, nor the rhythmic clatter of the waterwheel.
It was a deep, sickening underground heave that sent ripples racing across the surface of the drainage canal.
Out in the deep, uncharted center of the Black Fen—two leagues beyond the reach of the canals. There, the yellow fog lay thick as wool—a sound rose into the sky.
It was a huge, gurgling roar.
It sounded like three massive snake-like throats roaring in clashing all at once, wet with bile and shaking with ancient fury.
The blast wave rolled across the marsh, rattling the brass fittings on Teresa’s lye-tank and sending thousands of black marsh birds screeching into the overcast sky.
Rook Red-Mane went ghostly pale, his bow trembling in his fingers.
“The Broodmother,” Rook whispered, his voice cracking with terror. “The Three-Headed Rot-Hydra. She has smelled the burning of her shrines. She’s waking from the deep wallow.”
Giles adjusted his glasses. He looked toward the distant wall of yellow mist with cold, calculating eyes.
“An apex living entity with high territorial aggression,” Giles murmured. He pulled his slide rule from his vest pocket. “Mass estimated at forty tons. Armor profile: high-hardness organic hard shell with heavy curve.”
He tapped his rule against his palm, turning back toward the rail line.
“Our standard ballistae will suffer complete moving failure against that back shell. Kenneth, Borin. We need to look into sub-caliber sabot projectiles.”