An heavy iron wrench slammed twice against the bolted rim of a cast-iron flange, the sharp metallic ring cutting through the low roar of the forge.
At the far end of the castle's inner courtyard, the makeshift laboratory had transformed into a suffocating furnace of pure revolutionary ambition. The air inside the stone shed was thick and heavy, saturated with the metallic tang of superheated iron, gray clouds of coal smoke, and the sharp, pungent bite of burning sulfur.
Stepping across the threshold after leaving William and the militia recruits in the training yard, Arthur felt a wall of dry heat hit him full in the face, making beads of sweat prickle instantly beneath the collar of his dark-gray wool tunic.
He stopped just inside the doorway, his dark eyes locking onto the center of the workshop in quiet fascination.
There, leaning intensely over a massive stone workbench reinforced with thick oak beams, stood Prince Roland and seventeen-year-old Anna. Scattered across the table around them were dozens of freshly cast iron components, charcoal engineering blueprints, copper pipes, and crudely forged brass valves.
Anna had both of her small hands extended three inches above the seam of a heavy steel piston rod.
With breathtaking precision, she wasn't summoning a wide campfire flame; instead, she was projecting a thin, concentrated jet of blinding orange-white fire that hissed like a high-pressure plasma torch, fusing the two pieces of metal directly together.
Watching the molten seam glow and flow smoothly without a single flux bubble or slag crack, Arthur couldn't help marveling at the sight.
There were no dark necromancy chants here, no cursed green hellfire from the priests' stories. This was pure, applied thermodynamics channeled through the mind and body of a teenage girl whom the rest of the kingdom had tried to hang as worthless filth. Her complete elimination of metal impurities and the absurd, localized temperatures she generated out of thin air were the true miracles propelling Graycastle into the industrial era.
More importantly, the contraption taking shape on the stone table between them was not a musket or a cannon.
It was the very first prototype of the colossal project that would permanently rewrite the military, economic, and social destiny of this continent: Graycastle's first high-pressure steam engine.
To a modern engineer from Earth, the machine looked dangerously heavy, crude, and blocky—a patchwork of thick cast-iron cylinders, hand-filed brass joints, and an oversized boiler riveted together by the local blacksmiths. Yet in its mathematical and mechanical essence, sitting there in the middle of a twelfth-century feudal fortress, it was undeniably beautiful.
Hearing the click of Arthur's leather boots against the flagstones, Roland finally tore his eyes away from the piston assembly and looked up.
The young prince looked as though he had just crawled out of a coal mine. His royal tunic was tossed over a chair in the corner, his white linen shirt was black with grease and soot up to the elbows, his gray hair was damp with sweat, and his eyes were bloodshot and swollen from days of running on three hours of sleep.
— "If we cannot figure out a way to seal the head of this main cylinder properly, Arthur," — Roland grumbled, his voice hoarse from inhaling coal smoke all morning as he rapped the iron wrench against the side of the piston housing, — "then all of this iron is nothing more than a very expensive, overly complicated tea kettle."
Anna slowly closed her fingers, extinguishing her welding flame and wiping her damp forehead with the back of her sleeve as Roland pointed at the narrow gap around the piston rod.
— "The tolerances on the iron casting are as tight as Anna can make them without a mechanical lathe," — Roland explained in frustration. — "Even so, the moment we build up high-pressure steam inside the boiler and open the intake valve, the pressure blasts right past the edges of the cylinder head. Standard leather washers char and shrivel up in ten seconds under the heat, and plain wood ash paste cracks instantly. We need a packing material that won't melt, burn, or blow out under extreme steam pressure."
Arthur walked over to the workbench, pulling a rough three-legged wooden stool closer as he leaned in to examine the brass stuffing box and the valves Anna had just finished casting.
In the early days of Earth's industrial revolution, before synthetic rubber or Teflon existed, sealing high-pressure steam pistons had been one of James Watt's biggest headaches. Fortunately, Arthur's Intelligence 14 memory held the exact historical workaround.
— "Pure leather can't handle superheated steam, Your Highness, because the collagen fibers cook and shrink," — Arthur said, tapping the gap between the brass ring and the steel rod. — "For an immediate fix today, have the kitchen bring us two pounds of rendered mutton tallow mixed with a bit of beeswax and finely ground black lead—graphite from the North Slope. Then take long strips of unbleached linen rope, braid them tightly into a square ring, and boil the rope in that tallow-and-graphite grease before hammering it into the stuffing box."
Roland's bloodshot eyes widened slightly as he ran the material properties through his head.
— "A braided linen gland seal..." — Roland murmured, snapping his fingers. — "Of course! The hot steam will partially melt the tallow to lubricate the steel rod, while the wet linen fibers will swell up inside the brass housing and lock the pressure in!"
— "It will wear out every few days of heavy operation, so the operators will need to keep spare braided rings on hand," — Arthur noted pragmatically. — "However, in the long term, once the western concrete wall is completely secure and we open deep river trade routes toward the tropical southern marshes or the Fjord coast, we should send scouts to look for wild Hevea rubber trees. If we can harvest natural latex sap and vulcanize it with the sulfur from our mine, or eventually synthesize basic high-density polymers in your chemistry lab, our sealing problems will be solved forever. For this afternoon, though, tallow and linen are more than enough to prove that the pressure cycle works."
— "I will go fetch the tallow and linen from the kitchen storeroom right now, Your Highness," — Anna volunteered immediately, already turning toward the door with a determined nod.
For the next three hours, as the pale afternoon sun slowly sank behind the outer castle walls, the three of them worked without a single break.
They braided the greased linen packing, hammered it tightly into the cylinder collar, bolted the heavy iron cap down with every ounce of strength in their arms, and filled the thick iron boiler drum halfway with clean river water.
Finally, right as the first shadows of dusk crept across the courtyard, Roland tightened the last brass bolt and stepped back, wiping a streak of black grease across his cheek.
— "Alright, Anna," — Roland breathed out, his heart thumping against his ribs as he looked at the young witch. — "Apply a steady, medium flame underneath the boiler belly. Keep the heat uniform."
Stepping up to the brick firebox beneath the water drum, Anna extended both hands and released a wide, steady blanket of orange fire.
Within five minutes, a deep, rhythmic rumbling began to vibrate through the iron belly of the boiler. The water inside reached a violent rolling boil, and with nowhere to escape, the trapped steam pressure climbed rapidly inside the dome.
Hssssss—!
A thin wisp of white vapor hissed briefly against the newly packed linen-and-tallow seal around the cylinder head—and then, just as Arthur had predicted, the hot grease melted into the pores and the wet linen fibers swelled tight, choking the leak off completely!
Watching the rudimentary brass pressure gauge twitch upward, Roland wrapped a leather rag around his hand, reached out, and pulled the intake valve lever open.
CHUG—SHHHHHH—CLACK!
Pressurized steam roared through the copper transfer pipe and slammed into the chamber.
With a heavy, irresistible metallic shove, the solid steel piston rod shot forward out of the cylinder, turning the heavy cast-iron crank arm and spinning the five-hundred-pound iron flywheel half a rotation before the exhaust valve clicked and the rod snapped back for a second stroke!
CHUG-CLACK! CHUG-CLACK! CHUG-CLACK!
Faster and faster the heavy iron flywheel spun, shaking the stone floor beneath their boots as white exhaust steam puffed rhythmically toward the rafters of the shed like the breath of a waking iron dragon!
For ten full seconds, nobody inside the workshop said a word.
Arthur stood back with his arms folded, watching the spinning flywheel with a quiet, triumphant smile, while Anna stared wide-eyed at the iron arm moving entirely on its own—realizing for the first time in her life how invisible water vapor and fire could be turned into unstoppable physical muscle.
Beside the table, Roland Wimbledon simply laughed—a hoarse, exhausted, and utterly victorious sound that echoed over the rhythmic chugging of the first steam engine in Graycastle's history.
.
.
.
Late that night, long after the celebratory supper had ended and the entire castle had finally plunged into a deep, freezing sleep, Roland dragged himself up the stone stairs toward his third-floor quarters alone.
He was dead on his feet.
Every single muscle in his lower back, shoulders, and forearms was screaming with a dull, throbbing ache from hours of tightening iron bolts and hauling heavy castings in the workshop—manual labor that the pampered body of the Fourth Prince had never once performed in twenty years. All Cheng Yan wanted in the universe was to fall face-first onto his feather mattress and sleep for ten hours straight.
Pushing open the heavy oak door to his dark bedchamber, Roland stepped inside, kicked the door shut behind his heel, and walked on heavy legs over to his mahogany writing desk.
Reaching into the dark by memory, his fingers found the small flint striker. He flicked a spark onto the wick of the desk lamp, and as the warm amber light flared up to push back the shadows, Roland looked down at his chair—and froze solid.
His heart skipped a beat inside his chest.
He was not alone in the locked room.
Lounging comfortably in his high-backed leather chair right behind the desk, with one booted leg crossed casually over the other, was Nightingale.
Unlike the previous night, she had pushed her heavy dark hood all the way back off her head, allowing her long, wavy silvery-blond curls to tumble freely over her shoulders and catch the soft golden glow of the lamp.
And to Roland's absolute, blood-pressure-spiking despair, the lethal assassin had a thick stack of his private engineering notebooks and secret administrative parchments spread out across the desk, flipping through his top-secret blueprints with one ungloved hand as casually as if she were skimming a cheap summer romance novel at the beach!
— "You know, Your Highness, it seems the tavern rumors in the capital really are the most useless, unreliable currency in all of Graycastle," — Nightingale said without even lifting her deep blue eyes from the page in her hand, her soft, melodious, and effortlessly teasing voice echoing off the cold stone walls. — "In every wine hall from King's City to Redwater, people swear up and down that the infamous Fourth Prince is an ignorant, lazy, and hopeless drunkard with the strategic foresight of a blind goat. And yet... look at this exquisite technical drawing you have hidden under your tax ledgers. You call this contraption a 'Steam Engine,' don't you?"
Standing two paces in front of his own desk, Roland felt a thick vein throb violently against his temple as a wave of pure irritation washed over his exhaustion.
For the love of God!, Roland cursed silently inside his head, glaring at the blonde woman in his chair as his sleep-deprived brain lost all patience for midnight break-ins. I swear to heaven, whatever deity created magic in this world needs to be shot for handing out invisibility powers! Do the witches of this Association simply not believe in the basic human concept of privacy?! Walking in and out through the solid walls of my locked bedroom whenever she feels like it... does she think my royal quarters are a damned public tavern with a revolving door?!
Despite cursing her up and down in Mandarin, English, and Graycastle common tongue inside his skull, Roland forced his face to remain calm and calculated on the outside.
He wasn't suicidal. He knew very well that shouting like a spoiled brat at an apex assassin who carried silver-plated throwing knives and could vanish into thin air in a millisecond was a terrible career move.
Letting out a slow breath through his nose, Roland folded his arms across his chest and adopted the calm, composed posture of an engineering professor addressing a curious student.
— "Yes. Those are the assembly blueprints for our first external-combustion power engine," — Roland replied evenly. — "Though you don't need to look at the parchment as if it were a magic scroll. Without Anna's extraordinary thermal control to melt the iron molds and weld the containment cylinders without seams, those drawings would never be anything more than spilled charcoal ink and impossible daydreams locked inside my drawer."
Nightingale finally raised her eyes from the parchment, tilting her head slightly as she used the tip of a slender, pale index finger to trace the intricate cross-section of the double-acting piston and slide valve drawn in charcoal.
— "I watched the three of you cheering over that noisy iron barrel in the shed right before supper," — Nightingale admitted, genuine curiosity shining in her blue eyes. — "What exactly does this heavy pile of iron tubes and spinning wheels do that is so miraculous you are willing to pour the last of your castle's gold into building it?"
The moment she asked about the practical application of the machine, every trace of bone-deep fatigue seemed to evaporate from Roland's body.
His posture straightened, his bloodshot gray eyes lit up with a fierce, feverish brilliance, and the passionate twenty-first-century visionary completely took over the young prince.
— "That 'noisy pile of iron tubes,' Nightingale, can perform—without a single minute of rest—the continuous brute labor of one hundred grown men and twenty draft horses combined," — Roland declared, stepping up to the edge of the desk as his voice rang with quiet power.
Nightingale's eyebrows rose slightly as Roland leaned forward, his hands gesturing in the air:
— "Unlike human laborers or pack mules, this machine never gets tired, its muscles never tear, it never complains about the cold, and it doesn't bleed," — Roland continued, his voice magnetic. — "As long as you feed its firebox with coal and its belly with water, it will run twenty-four hours a day through the worst blizzard of the year. We can hook it up to mechanical pumps to drain deep, flooded mine shafts in hours. We can connect it to giant trip-hammers to forge tons of high-grade steel every single day. And once we mount larger versions onto heavy barges and iron tracks, it will haul hundreds of tons of grain, ore, and artillery across rivers and mountains faster than the fastest warhorse in Graycastle!"
Inside the quiet bedchamber, Nightingale sat completely still for a long moment.
The playful, teasing smile had vanished from her lips as her sharp mind absorbed the surreal, world-shaking promise contained inside the strange prince's words.
A machine made of common iron that could replace a hundred men, run on coal and fire, and never grow tired?
Suddenly, Nightingale looked back down at the charcoal blueprint on the desk. With slow, methodical care, she folded the stiff parchment sheet into a neat square, lifted the edge of her dark cloak, and slipped the drawing straight into the hidden inner pocket of her tunic!
— "In that case, Your Highness, I will be taking this 'future' drawing with me," — Nightingale stated, her tone dropping all playfulness and turning dead serious. — "The Witch Cooperation Association also has sisters who awakened the natural gift of fire and heat. When our caravan finally reaches the Sacred Mountain in the north, they can use this blueprint to forge a 'tireless iron heart' of our own—to pump water, build walls, and keep our sanctuary warm, far away from the reach of mortal kingdoms."
— "Hey—hold on a second! Put that back!" — Roland's eyes widened in alarm as he took a sharp step around the desk, reaching out a hand to stop the brazen theft of his most valuable industrial blueprint. — "First off, you can't build a high-pressure boiler in a mountain cave without precision valves or a blast furnace! And second, that is a classified military and state project under—"
Before Roland could take another step, Nightingale simply raised her pale right hand in a calm, elegant "stop" gesture that froze the prince in his tracks.
— "Do not get angry so quickly, Your Highness. I am not a common street pickpocket, Roland Wimbledon," — Nightingale reprimanded him gently, a proud glint flashing in her blue eyes. — "My sisters and I were raised with honor. I would never take something of great value from your table without leaving behind a gift of equal—or far greater—worth in exchange. Look closely at what I am placing on your desk before you complain about a piece of paper."
Lowering her hand to her waist, Nightingale slipped two fingers inside a small leather pouch on her belt and pulled out a tiny, fragile cylinder of parchment.
Setting it down gently in the exact center of the dark mahogany desk under the lamp, she tapped it once with her fingernail.
The scroll was minuscule—made of ultra-thin, oil-treated waterproof paper, rolled tighter than a cigarette, and barely longer than the first joint of a man's index finger, sealed shut with a tiny drop of unremarkable gray wax.
Roland blinked, his annoyance over the stolen steam engine diagram instantly giving way to a sharp, prickling suspicion.
Stepping up to the desk, Roland picked up the tiny roll of paper between his thumb and forefinger. Using his thumbnail to crack the generic gray wax seal, he carefully unrolled the tissue-thin strip and held it close to the amber flame of the oil lamp.
As his gray eyes scanned the cramped, coded, and visibly frantic lines of ink written across the tiny strip, every single drop of blood drained from Roland's face.
His skin turned as pale as chalk, his breath caught in his chest, and an ice-cold shiver—ten times more bone-chilling than any story Iron Axe had told about winged Hybrid monsters—crawled straight up his spine.
— "This... what is this..." — Roland whispered, his voice trailing off as the tiny piece of paper trembled slightly between his fingers.
— "That, Your Highness, is a dirty little secret note that I intercepted less than an hour ago," — Nightingale explained, her voice light and almost cheerful on the surface, though her sharp, predatory eyes were locked onto Roland's face, analyzing every microexpression of shock and terror. — "It was tied to the leg of a trained carrier pigeon hidden inside a false wicker basket in the southern servant tower, waiting to be released toward the capital before dawn. And the author of that affectionate little letter? None other than your lovely, quiet, and timid personal head maid—Tyre."
Nightingale leaned back in the leather chair, crossing her arms with a dry, ironic smile:
— "It would appear, my dear Prince, that the famous 'castle harem' the townsfolk gossip about isn't quite as lovingly devoted to you as you thought."
Roland didn't even hear her joke; his mind was racing at a thousand miles an hour as he stared down at the cramped handwriting.
He remembered Tyre clearly.
She was a slender nineteen-year-old girl with a pale, delicate face and a perpetually frightened, submissive demeanor who moved through the castle corridors like a quiet mouse, bringing him his morning washbasin and making his bed.
Searching through the fragmented, disgusting memories of the original Roland Wimbledon, Cheng Yan recalled the ugly history behind the girl. Back in the King's City, and later during the journey here, the pathetic, arrogant sixteen-year-old original prince had developed an obsessive, unrequited infatuation with the pretty young maid—cornering her in hallways, harassing her, and eventually forcing her to be transferred to Border Town to occupy the servant room right next door to his royal bedchamber for his personal convenience.
Ever since Cheng Yan had woken up inside this body on the day of Anna's execution, however, the "new" Roland had been so completely consumed by survival—by cement kilns, Duke Ryan's trade traps, gunpowder, and steam engines—that he hadn't paid two seconds of attention to the girl. To him, Tyre had been nothing more than a quiet, harmless piece of castle furniture who swept the rug and stayed out of his way.
Never in a million years had he suspected that the timid maid sleeping in the room right next door was a venomous viper holding a poisoned blade to his throat!
Roland looked back down at the tiny strip of waterproof paper in his hand.
The note bore no formal signature or family crest, yet its message was unmistakable and terrifyingly explicit. Written in short, urgent phrases meant for an unnamed master back in the King's City, the letter reported on the "inexplicable failure of the autumn dose," expressed deep fear over "the target's sudden change in temperament and strange metal weapons," and answered the master's furious inquiry as to why the Fourth Prince was still alive and issuing royal decrees on the frontier!
The assassination on day one..., Roland thought, his stomach churning violently as a wave of cold nausea hit him.
Suddenly, the final, terrifying puzzle piece of his own transmigration locked into place inside Cheng Yan's head.
The poison in the wine cup didn't fail at all, Roland realized, his fingers clenching tight around the edge of the mahogany desk. Three weeks ago, on the morning of Anna's execution, the real Roland Wimbledon drank the slow-acting poison Tyre put in his morning goblet. The useless, arrogant original prince really did suffer cardiac arrest and die right there in his chair before going to the square! The only reason this body stood up and walked out to the gallows... is because my modern soul fell into the empty corpse a second after his heart stopped!
The person who had already murdered the Fourth Prince once was sleeping less than thirty feet away down the corridor right now—and she was asking her master in the capital for instructions on how to finish the job a second time!