"Whatever this place was originally built for, it is now nothing more than an obstacle," Qin Mo said. "One more ancient relic standing in our way."
His voice was cold, almost flat, but his gaze remained fixed on the titanic passage ahead as if he were already measuring how much of it he would have to break, bend, or outthink.
The passage was a monument to forgotten Imperial engineering. It was not merely a tunnel, but a buried arterial route large enough for armored columns, freight convoys, and even Titan-class war engines to pass through without brushing the vaulted ceiling. Reinforced plasteel ribs vanished into the dark above them. Adamantium support bands crossed the walls at regular intervals, many corroded by millennia of damp, chemical runoff, and neglect, yet still stubborn enough to make time itself look impatient.
Old battle scars marked the structure. Shell impacts. Melted gouges. Places where something heavy had struck the walls hard enough to ripple the outer plating but not enough to breach it. Rust had gathered in the wounds like dried blood.
Beneath the grime, faint sigils still showed in places. Some were Imperial. Some were older. A few predated even the Mechanicus iconography Qin Mo had learned to recognize, reduced now to half-buried lines beneath oxidation and dust. Whatever knowledge had built this passage had been lost, buried, classified, or deliberately forgotten. In the Imperium, those were often the same thing.
Klein crouched on one knee and swept aside a layer of dust with his gloved hand. The ferrocrete floor beneath was scratched with a rough schematic, not newly drawn but recently uncovered, its lines reinforced by finger marks and fragments of charcoal. His fingertips traced the old markings with the care of a man reading the handwriting of a dead engineer.
"As far as I know, this passage is lined with an ancient self-destruction mechanism embedded within its structure. It's nothing fancy, but it's reliable and effective."
His voice had become measured and technical. The sarcasm he used around soldiers and officers vanished whenever he spoke about machinery that could kill thousands of people by functioning exactly as designed.
"The mechanisms are embedded with demolition charges, linked to a self-repairing detonation switch."
He tapped several points on the schematic, each one corresponding to a structural band vanishing into the darkness ahead.
"Once activated, the first layer of charges detonates. Massive slabs of reinforced plasteel and ceramite collapse inward, blocking the tunnel."
Qin Mo folded his arms. "That's not the real issue, is it?"
Klein's expression darkened. He did not answer immediately. Instead, he looked down the passage as if he could see the disaster still sitting inside the walls, patiently waiting for someone foolish enough to test it.
"A second layer follows. The old records call them thermobaric charges, but that is only the closest Administratum translation. They behave more like distributed melta charges."
He drew a slow line along the schematic with one finger.
"The first collapse creates the obstruction. The second layer turns that obstruction into a trap. It floods the broken structure with superheated liquefied metal, ceramic slurry, and molten reinforcing alloy. Every crack fills. Every gap seals. The wreckage fuses into one continuous mass."
Klein looked up at Qin Mo.
"Once the system completes its work, the entire nine-hundred-kilometer route becomes an artificial mountain buried inside the hive. No seams. No maintenance voids. No crawlspaces. Nothing large enough for a rat to squeeze through."
He exhaled sharply, equal parts admiration and disgust.
"By the Emperor… I cannot decide whether the man who designed this was a genius, a lunatic, or a genius because he was a lunatic."
With that, Klein lifted the schematic sheet from the floor, shook dust from its edge, and handed it to Anruida.
"You know quite a bit about these self-destruction mechanisms," Qin Mo observed.
His tone was casual enough, but his eyes remained on Klein. In the Underhive, useful knowledge always had a history. Sometimes that history was harmless. Usually, it had teeth.
Klein grinned, tapping his chestplate with mock pride.
"Of course. My family is the oldest engineering dynasty on this planet. In fact, my family's entire rise to prominence is tied to these self-destruction systems."
Anruida glanced at him with open skepticism. Klein ignored it. Like many men from families with long histories, he had inherited both the pride and the embarrassment.
"Roughly 1,700 years ago, one of my ancestors was entrusted with a classified project by the Planetary Governor himself. It took him thirty years to extract a single ancient melta charge from these walls."
Qin Mo raised an eyebrow.
"Impressive. What did the Governor use it for?"
Klein smirked.
"Tyrone Hive was in the middle of a rebellion, an uprising led by an unknown cult against the planetary defense forces. Everyone assumed the Governor would use the charge for military purposes against the insurgents. Instead, he detonated it inside a rival noble house's district, melting their entire estate into slag."
Anruida stared at him.
"During an active rebellion?"
"Especially during an active rebellion," Klein said. "That was the convenient part. Everything could be blamed on battlefield necessity, rebel sabotage, or divine judgment, depending on which report reached the spire first."
Qin Mo snorted.
"Seems such treachery is tradition among Governors, then."
"Oh, their family has plenty of traditions," Klein laughed. "None of them good."
The three men stood together at the edge of the sealed route, their silence filled by the distant hum of the Underhive. Somewhere behind them, soldiers shifted uneasily, boots scraping on metal. A few pretended not to listen. Others stared into the blocked passage as if waiting for the ancient mechanism to wake and swallow them too.
Qin Mo exhaled slowly and raised one hand.
The air tightened. Dust lifted from the floor in a thin ring around his boots. The loose scraps of metal near the obstruction trembled, then stilled as his will passed over them and reached deeper into the fused mass.
Klein watched with forced calm.
He had seen Qin Mo build a fortress by commanding metal to move. He had seen alloy soften, fold, and harden into shapes no forge on Talon I could reproduce. But that had been construction. Controlled reshaping. Sections of material pulled into place and given purpose.
This was different.
This blockade was not a pile of debris. It was a deliberate, continuous plug of fused plasteel, ceramite, slag, and adamantium fragments spread across impossible distance. Compared to the scale of it, the fortress Qin Mo had raised from a ruined hab-block suddenly seemed like a child's shelter made from scrap.
Still, Klein said nothing. It was worth trying. In the Underhive, impossible things had become practical enough that dismissing them out of hand felt unwise.
Qin Mo focused.
The metal obeyed.
At first.
The outer layers of wreckage softened. Liquefied plasteel and adamantium-rich slag shifted like thick, glowing rivers beneath a skin of cooled metal. Sections of the blockade sagged, flowed downward, and began to peel away from the main mass. The sound was deep and wet, like the groan of a furnace choking on its own contents. Heat shimmered through the air, though Qin Mo kept the temperature from spilling outward enough to kill the men behind him.
Then the material reformed.
The moment he moved one portion aside, stresses redistributed through the rest of the fused plug. Molten alloy seeped back into voids. Support layers settled. The blockade did what it had been designed to do: it healed into obstruction. Not intelligently, but mechanically, through sheer redundancy and the stubborn physics of a system built to deny passage forever.
Qin Mo's jaw tightened.
This was not construction. This was excavation.
And excavation required removing mass, not merely persuading it to take a new shape. Worse, it required removing that mass without letting the surrounding structure collapse, without triggering dormant secondary mechanisms, and without turning the passage into a nine-hundred-kilometer death furnace.
The problem was not that the metal resisted him.
The problem was that there was too much of it.
At that moment, Qin Mo remembered what the Shapeshifter had said.
His power was returning.
That meant it was not yet complete.
....
Half an hour later, Qin Mo lowered his hand.
"Pointless."
Qin Mo shook his head.
"This is like trying to fill an ocean with stones."
Anruida frowned. The metaphor clearly meant nothing to him, but the frustration behind it was obvious enough.
Klein understood immediately. He nodded with a grimace.
"Too much mass. Too much length. Too much self-sealing material."
"Is the entire blockage fused down to the last gap?" Qin Mo muttered, more to himself than to the others. His mind was already moving through alternatives, rejecting them as quickly as they formed. "If I could get inside and plant melta charges in the gaps…"
His body distorted.
It was not the shimmer of a void shield or the blur of a teleport. Qin Mo simply stopped interacting with the wall in the way a human body should. The air around him warped, his outline thinning until his armor seemed half-reflected in the metal ahead. Then he stepped forward and passed into the obstruction as if solid matter had become mist.
Klein and Anruida watched him disappear.
Neither man reacted with the shock such a sight deserved. They had both reached the point where Qin Mo passing through solid metal was no longer the strangest thing that had happened that week. That realization disturbed Klein more than the ability itself.
....
Ten minutes later, Qin Mo re-emerged from the wall.
"No gaps. The molten metal filled every last crevice. There's no way through."
Klein sighed. Then, because he was an engineer and despair was not an engineering method, he forced himself to think.
"What if we don't dig?"
Qin Mo looked at him.
Klein's mind raced.
"Instead, we have people walk in formation around you, just like how you phased through the metal. Every kilometer, we'd create resting chambers. Would that work?"
Anruida looked from Klein to Qin Mo, visibly considering the madness of the suggestion and finding, to his discomfort, that it was not the worst idea he had heard today.
Qin Mo raised an eyebrow.
"You don't seriously think I'm going to be available at all times, do you?"
He gestured toward Anruida.
"What happens when I'm not here? How do they phase through then?"
Klein sighed in defeat.
"Fair point."
For a moment, only the Underhive spoke around them: distant machinery, dripping condensation, the faint buzz of faulty lumen strips, and the creak of ancient metal adjusting under impossible weight.
Qin Mo fell into deep thought.
Excavate the passage, or not?
The simplest solution was machinery.
Small-scale mining units equipped with high-efficiency metal-cutting tools could gradually chew through the obstruction, advancing meter by meter, sealing the walls behind them, venting heat, and hauling slag back through the fortress supply chain. Slow, ugly, but reliable.
The second option was brute force: massive macro-drills fitted with focused energy beams, gravitic stabilizers, and slag-extraction systems. They could burn through the fused wreckage faster, but the power requirements would be obscene, the heat dangerous, and the noise impossible to hide. Every heretic, mutant, spy, and ambitious noble within half the hive would eventually know exactly where the Imperials were digging.
Both answers were practical.
Both answers were also boring.
Qin Mo's thoughts moved beyond the tunnel.
Why was he thinking like a trapped animal clawing at a blocked burrow?
This passage was nine hundred kilometers of obstruction. Annoying, yes. Strategically important, yes. But in principle, it was only distance. A barrier between one region and another.
And distance was a problem he had always intended to solve on a far greater scale.
Warp travel was humanity's chain. It let the Imperium cross the stars, but only by throwing ships into a sea of daemons, storms, madness, and predatory unreality, then praying that a half-dead god's light and the calculations of Navigators would keep them from becoming debris, ghosts, or worse.
Qin Mo had known from the beginning that he would eventually need an alternative.
Why not begin now?
Not with a starship. Not with grand declarations about replacing the Warp. Those would come later. For now, he could begin with fundamentals. Controlled traversal. Local displacement. Dimensional bypass. Matter translation through alternate spatial routes. A stable method of crossing from one point to another without moving through the intervening obstruction.
A tunnel did not need to be opened if one could step around the concept of the tunnel entirely.
He stared at the collapsed passageway.
It was no different from the distance between star systems. Smaller in scale, but similar in principle.
There was always a way to cross distance.
The only question was whether he could build it before the galaxy found a new way to punish him for trying.
Qin Mo turned to Klein.
"Not only am I not going to excavate this tunnel. I'm going to reinforce it. I will make it impossible to breach or destroy."
Klein's face paled. For once, his clever mouth failed him for a full second.
"Are we going to be trapped in the Underhive forever?"
"No."
Qin Mo turned toward a nearby railcar.
"We will still be able to enter and exit. But not through this tunnel."
Klein stared at him, then at the sealed passage, then back again. Understanding did not come, but suspicion did.
"You have another route?"
"Not yet."
"That is not as reassuring as you seem to think it is."
Qin Mo ignored the complaint and turned to the nearby soldiers. Their officers straightened at once.
"Stop wasting time here.
If the regiments can't find Rebels to fight, they should begin training drills instead."
The order moved down the line quickly. Men who had been waiting beside equipment piles began gathering tools, weapons, and survey gear. Some looked relieved to leave the ancient passage behind. Others glanced back at it uneasily, as if Qin Mo had just declared war on geometry itself.
Klein remained beside him a moment longer.
"You are serious," he said quietly.
Qin Mo did not look away from the obstruction.
"Yes."
"About not digging."
"Yes."
"About making this thing even harder to breach."
"Yes."
Klein rubbed both hands over his face. "By the Emperor, command meetings with you are going to kill me before the rebels do."
Qin Mo's mouth twitched slightly.
"Then train harder."
....
Back at the Fortress
Qin Mo had decided.
He would begin a long-term research project. Not a battlefield improvisation. Not another emergency weapon built out of scrap and necessity. A real technological foundation, one that could grow into something large enough to matter beyond the Underhive, beyond Talon I, perhaps beyond the rotten assumptions the Imperium had mistaken for inevitability.
But research required time. Time required security.
Security required people who were not starving, panicking, or waiting for the next breach alarm to drag them from their beds.
So before Qin Mo turned fully toward the problem of dimensional traversal, he ensured the hive below his command could survive without him standing over every wall.
If the Shapeshifter's warnings were even partially true, then the Genestealer Cult had not been the end of the danger. It had been one layer. One infection among others. Somewhere above them, corruption might already have reached the lower hive, the spire, the Governor's court, or whatever passed for loyal authority on this world.
Leaving the Underhive was not enough.
They had to be ready to remain here. To hold. To expand. To fight upward when the time came.
Qin Mo issued new directives to the AI Core.
Logistics drones shifted priority within minutes. Salvage routes changed. Excavation teams were reassigned. Fabrication chambers began producing standardized structural ribs, habitation modules, water purification stacks, power conduits, ration processors, medicae stations, and turret housings. What had been a fortress network would become something larger.
A city.
No. A fortress-city.
An Imperial stronghold built in the belly of the Underhive, not pretty, not ceremonial, not designed to impress nobles or satisfy Mechanicus ritual aesthetics. Designed to endure. Designed to feed people, arm people, shelter people, and make any enemy advance pay in bodies for every meter.
Massive foundries would anchor the industrial districts, each one protected by overlapping void-hardened shutters and internal kill corridors. Munitions factories would sit below reinforced layers, close enough to the rail lines and drone shafts to supply the front quickly, but compartmentalized so one explosion could not gut the whole city.
Defensive turrets would cover every major avenue, transit throat, lift shaft, ventilation canyon, and manufactorum approach. Anti-infantry weapons would sit low and concealed. Heavy cannons would occupy recessed bastions. Mobile fire support drones would wait in armored cradles beneath the streets, ready to rise through launch shutters the moment enemy concentrations were detected.
Civilians would live beneath those guns.
That part mattered.
The Imperium treated civilians as labor, tithe mass, bodies, mouths, or future corpses depending on which office filed the report. Qin Mo could not build a utopia in the Underhive. He did not have the luxury, resources, or time. But he could build something better than the usual Imperial bargain of misery in exchange for a lasgun when the walls broke.
Habitation blocks would be ugly but sealed. Ventilation would function. Water would be purified before consumption instead of after enough people died to justify repairs. Food would be distributed by need, not rank, bribe, or proximity to a quartermaster's cousin.
Every citizen would work. Factory shifts by day. Maintenance rotations. Salvage processing. Agriculture in controlled fungal bays. Ammunition packing. Medical support. Courier duty. Emergency construction.
And when war reached the walls, every able-bodied adult would know where to go, which weapon locker to open, which corridor to defend, which children to evacuate, and which doors to seal behind them.
The central districts would house hardened bunker networks. Not only command shelters, but schools.
Qin Mo stared at the projected plans for a long time before approving that section.
The schools would not be gentle places. There would be no grand halls of art, no gardens beneath artificial sunlight, no soft lectures about civic virtue delivered by men who had never seen a trench. The children of the Underhive had already learned too much about fear. Qin Mo intended to teach them how to survive it.
Literacy. Basic mathematics. Engineering habits. First aid. Weapon safety. Hazard recognition. Imperial law where useful. History where not actively poisonous. Tactics appropriate to age. Emergency drills. The difference between courage and stupidity.
During peace, the central bunkers would be classrooms.
During war, they would become shelters.
The walls would be thick enough to survive artillery. The air systems would be independent. Food and water would be stored behind sealed doors. Every route inward would pass through choke points watched by guns.
No luxuries like sports or fine arts. Not yet.
Perhaps one day.
For now, survival came first.
Qin Mo was not building paradise.
He was building the minimum conditions required for human beings to stop dying from preventable incompetence. In the Imperium, that alone bordered on revolution.
Food and clean water would be freely given. Shelter would be assigned. Work would be mandatory. Defense would be universal. Discipline would be strict, but not pointlessly cruel.
No one would starve because a clerk lost a form.
No wounded man would be denied treatment because his regiment lacked the right stamp.
No child would be left in a hab-corridor during bombardment because the nearest noble bunker had decorative locks.
That much, Qin Mo could enforce.
With the city plan set into motion, he finally turned away from the projected fortifications and opened a new file in the research core.
The title remained blank for several seconds.
Then he filled it in.
Humanity's Version of Necron Phase Technology.
A means to traverse alternate dimensions.
A method to bypass distance, matter, and obstruction without touching the Warp.
A foundation for movement through reality's hidden architecture.
A way to end mankind's dependence on the Sea of Souls forever.