The transition to a protein-vat economy had stabilized the mountain's stomach, but it had significantly increased its "Optical and Magnetic Bleed." Every electrolysis cell, every steam-turbine, and every arc-lamp pulsed with a rhythmic electromagnetic signature that leaked through the limestone like a beacon in a fog. On the surface, Arch-Magister Vane's sky-ships had ceased their blind bombardment. Instead, they hovered in a geometric grid, dropping "Sondes"—weighted iron spheres that hissed as they sank into the marshy perimeter of the Salt-Spur. These weren't bombs; they were magnetometers. Vane was no longer trying to crack the mountain; he was trying to "X-ray" it, looking for the tell-tale magnetic hum of the geothermal bore to guide a single, catastrophic precision strike.
Kael felt the warning at the base of his skull shift into a persistent "Cold-Static." It was a prickly, electrical sensation, as if the air around him were being stretched thin. The "Golden Finger" was signaling a threat of detection—the most dangerous kind of vulnerability for a fortress that relied on being a void. To counter the Imperial sensors, Kael initiated the Faraday Shroud—a Tier 14 project to encase the mountain's primary energy arteries in a layered defense of copper mesh and lead-shielding, effectively turning Ashfall into a "Magnetic Ghost."
The technical core of the Shroud was the Galvanic Grounding-Ring. Kael engineered a massive, circular conductor made of reclaimed Imperial telegraph wire and foundry-cast copper plates. This ring was installed around the primary geothermal turbine, designed to "Catch" the stray magnetic flux and divert it directly into the mountain's deep-water aqueduct. By "Grounding" the electromagnetic noise into the flowing river, the mountain's signature was washed away by the natural conductivity of the earth.
"We are building a mirror for their magnets, Elms," Kael said, his voice muffled by the heavy lead-apron he wore as they inspected the turbine hall. "Vane is looking for a pulse. We're going to give him a flat, dead line. If we don't mask the bore, they'll drop a 'Lightning-Javelin'—a high-altitude kinetic rod—right through our ceiling and straight into the boiler."
The grit of the construction was a brutal exercise in manual dexterity. The Tier 0 laborers and the Aspirant electricians had to wrap miles of the copper mesh around the vibrating, scalding-hot steam pipes and high-tension galvanic lines. The mesh was sharp, like a thousand tiny needles, and the lead-shielding was heavy, requiring teams of six men to hoist a single plate into position. The air in the turbine hall was thick with the smell of hot metal and the ozone of stray sparks, a constant reminder of the energy they were trying to hide.
Socially, the "Magnetic Blackout" added another layer of isolation to the citizen's lives. To ensure the Shroud's effectiveness, Kael had to strictly limit the use of portable arc-lamps and electrical tools in the upper tiers. The mountain grew darker, the light restricted to the "Safe-Zones" of the Green Ring and the Protein Vats. The people moved through the corridors with dim oil-lanterns, their world shrinking once again. The psychological "grit" of this deepening gloom was palpable; the sense of being "hunted" by an invisible eye from the sky created a persistent, low-grade anxiety that even the new protein-pulp could not soothe.
However, it was during the "Grit-Work" of the Shroud's expansion that the nature of Ashfall changed forever.
In the deepest reach of Tier 17, far below the Protein Vats and well into the "Deep-Basalt" zone, a low-level excavation worker named Silas was carving a channel for a grounding-rod. Silas was a former northern refugee, a man used to the stubborn resistance of surface granite, but here, the basalt felt... different. As his steam-drill bit into the stone, the resistance didn't just yield; it vanished.
The drill-head plunged into a void with a shrill, metallic scream.
Silas pulled back, his oil-lantern flickering in a sudden, cold draft that smelled not of damp earth or ammonia, but of ancient, dry dust and a hint of something metallic—like old bronze. He swung his pick, clearing a jagged hole in the rock, and stared through the gap.
He wasn't looking into a natural cave.
Bathed in the dim amber glow of his lantern was a hallway that defied every principle of Ashfall's utilitarian engineering. The walls were not raw limestone or braced iron; they were composed of a seamless, obsidian-like stone, polished to a mirror finish. Inscribed along the cornices were geometric patterns that pulsed with a faint, residual violet light—a luminescence that had survived for untold eons in the dark.
"Baron!" Silas's voice echoed up the acoustic pipes, cracking with a mixture of terror and awe. "Baron, come down! I've... I've broken through the world!"
Kael descended the deep-rail in silence, his internal "Golden Finger" warning completely still for the first time in weeks. When he reached Silas and stepped through the breach, his breath hitched. This was not a geological formation. This was a Pre-Imperial Arterial, a remnant of a civilization that had mastered the deep-earth long before the first Stone-Shaper had even touched a hammer.
The hallway stretched miles into the darkness, angling toward the southeast—far past the borders of the Barony and deep under the "Forbidden Wastes" that lay beyond Vane's blockade.
"It's a 'Ghost-Road', Elms," Kael whispered, touching the cool, smooth obsidian. The stone didn't feel like stone; it felt like a solidified liquid, perfectly preserved. "This doesn't show up on any Imperial map. If this path holds, it's a way out. We could bypass the blockade entirely, moving goods or people under the very feet of Vane's army without them ever hearing a sound."
But as Kael took a single step forward, his boot clicked against a floor tile that felt slightly too light.
His internal "Ping" didn't just fire; it exploded into a sensory roar. He froze, his foot hovering an inch above the polished floor. From the darkness ahead, the sound of a thousand tiny, rhythmic clicks began to resonate—the sound of ancient, clockwork mechanisms waking up after an age of slumber.
"Nobody move," Kael commanded, his eyes fixed on the violet geometry of the walls. "This isn't just a road. It's a 'Labyrinth'. And the builders didn't leave the doors unlocked."
The discovery was a beacon of hope—a potential exit from their frozen cage—but the trepidation was absolute. They had found a path out of the Empire's reach, but they had entered the reach of something much older, and far more precise.