A Clue
The waterway management office sat beside a valley a little farther down from the eastern outskirts of the main keep.
In daylight it would have been nothing but crumbling stone walls, a collapsed sluice gate, and weeds — but night made everything sharper. What you couldn't see, you felt all the more.
We kept our voices low. I took the lead, with the Grand Duchess and the Imperial Princess close behind. Dein and four knights spread out to either side, holding their distance. Father had stayed behind at the keep. The barrier core was barely clinging to life; he couldn't leave his post.
The path down was slick. The earth beneath the frozen leaves was wet, and the closer we drew to the watercourse, the colder and muddier the stones underfoot became. With every breath, a thin plume of white scattered and was swallowed by the dark.
The Grand Duchess asked very quietly,
"Your steps are full of certainty, Sir Elverhart."
I answered without looking back.
"This is the place."
"You mean the origin point of the contamination?"
"Origin point isn't quite right… It's more accurate to call it a position well suited for spreading it."
The Imperial Princess picked up from behind.
"Explain the difference."
I slowed my pace a little and pointed down into the valley. Under the faint moonlight, a single dried-up water channel stretched like a black line.
"The wells, the stockades, and the outer watch posts are dotted at intervals. If this were natural contamination, it should spread along a single continuous line — but right now, only the places where people are most likely to collapse are rotting first, one after another."
The Imperial Princess listened in silence.
"And here, the watercourse and the underground lines run together. Handled properly, you could shake the barrier's resonance, foul the water, and disrupt the residents' routes of movement all at once."
The Grand Duchess murmured low,
"A place where someone with malice could set the board."
"Yes."
At that point Dein bent forward ahead of us.
"Sir Rion."
I stopped. Where he pointed, faint marks remained in the dirt. Two human footprints. One set of hoofprints. They weren't old. Even in air this cold, the edges hadn't fully hardened yet.
"Not a full day. Within a few hours."
At my words, the Imperial Princess narrowed her eyes.
"Someone came through ahead of us."
"So it seems."
I raised a hand and spread the formation lower.
"Don't cover the lanterns. Just don't hold them high."
The knights obeyed at once. The closer we drew to the waterway office, the sharper the smell became. The stench of stagnant water, and beneath it a very thin thread of fragrance. It was subtly different from the rare incense I'd smelled in the Imperial Palace — far cheaper and denser than the ordered scent of the Records Bureau. A smell left behind by someone trying to cover a scent, and failing. As if someone had hurriedly applied something else to mask a habit long steeped into their body.
I said quietly,
"I smell a person."
Dein frowned.
"A person? Not an animal…?"
"Right. At least here."
The old management office was more intact than I'd expected. One side of the roof had caved in and some of the wall stones had crumbled, but the front door had been recently patched with a crooked plank. It didn't carry the dead air of a sealed place — it smelled like a space someone had forced into continued use.
The Imperial Princess jerked her chin.
"The window."
Two knights split off to either side. The Grand Duchess was already looking toward the collapsed sluice gate on the right of the building. I examined the ground before the front door. Footprints. And a very small black speck. I crouched and touched it with a fingertip; the dried residue crumbled. A texture similar to the contamination that had clung to the well.
"Your Highness."
The Imperial Princess came closer.
"What is it. Tell me."
"It seems it was brought in from outside and spread. Not produced here."
The Grand Duchess looked at the fragment as well and said low,
"So someone carried it here themselves."
That was actually good news. If it was human work rather than a natural disaster, there would be traces left behind.
The Imperial Princess stood at the doorway.
"Shall we open it?"
I didn't touch the door. I listened. Inside was quiet. Too quiet. Not even the stir of a single animal. Like a room where someone was holding their breath.
"Wait."
At my word, the knight's hand stopped. I looked down at the gap beneath the door. In the darkness, a single faint red point appeared and vanished. An ember. Someone inside had just put it out — or it was still burning.
"There's someone inside."
The Imperial Princess's eyes went cold.
"You're certain?"
"…Yes."
She gave the order without ornament.
"Break it down."
Bang—!
The wooden plank flew inward and dust billowed up. Two knights stormed in first, and the Grand Duchess's pale blue-white threads swept thinly across the floor. The interior wasn't large. One old control room, the lever apparatus that once worked the rear sluice gears, an aged waterway diagram hanging on the wall. And in the middle of the floor, a toppled oil lamp.
As for a person—
"Behind!"
The instant my voice broke, someone burst from the shadow of the collapsed inner wall. A short blade flashed toward a knight's throat. One knight blocked on reflex, but the angle was late. If it had gone through clean, his neck would have opened.
The Imperial Princess's golden line flew first.
Fwaat.
Light grazed the black shadow's wrist. The knife spun through the air and clattered to the floor, and at the same moment the Grand Duchess's ice threads coiled around an ankle. The figure pitched forward. Two knights pinned him down at once.
The sound of short, ragged breathing filled the room. The fallen man was young. Not dressed as a management office laborer, nor as a territorial soldier. Plain commoner's clothes at a glance — but the backs of his hands and his palms were smooth. Hands closer to a messenger's. And yet his face looked familiar.
Dein gritted his teeth first.
"…This bastard."
I looked at him.
"You know him?"
Dein answered roughly.
"A runner from the eastern market. He'd been scarce for about half a year…"
The man clenched his jaw and said nothing. Blood ran from his wrist, but the light in his eyes was still alive. Not the kind you could take lightly. At the very least, not some low-end pawn swayed by a few coins.
The Imperial Princess stepped closer and looked down at him.
"Tell me your name."
The man kept his mouth shut. The Imperial Princess spoke without a smile.
"Fine. You don't have to talk. Now that we've come this far, you won't last long anyway."
At that, the man's jaw shifted by the barest fraction. He seemed to be calculating something. I turned my attention to the office interior before he could finish. The two sluice-control levers at the back had been moved recently. The rust had been cleanly scraped away, and wet footprints trailed across the floor beside them. And on the innermost wall, a newly drawn line. An inked addition over the waterway diagram.
I stepped closer and studied it. A provisional flow chart linking a sealed underground channel, the eastern well of the main keep, and the drainage ditch beneath the outer stockade into a single path. Someone had prepared this for a long time.
I murmured very low,
"This is… impossible."
The Imperial Princess asked from behind,
"What did you find?"
I stepped aside. The Imperial Princess and the Grand Duchess looked at the diagram together. The Grand Duchess seemed to grasp it first; her eyes narrowed.
"A path for spreading the contamination."
The Imperial Princess reached the answer just as quickly.
"Not merely shaking the relay lines — in the order that would let fear spread the fastest."
I pointed to the time notations written along the bottom of the diagram. First the well. Second the stockade. Third the outer watch post. And last — the inner storage water of the main keep.
My breath went cold.
"Your Highness."
The Imperial Princess turned her gaze to me.
"The next place these people mean to strike is the storage water."
The Grand Duchess checked the control levers at once.
"It hasn't been fully opened yet. About halfway."
I turned and looked down at the pinned man.
"When were you going to open it?"
He still refused to speak. Dein roughly seized him by the collar and hauled him up.
"You son of a—"
"Let him go."
At my words Dein froze. I slowly crouched in front of the man.
"You think keeping your mouth shut and dying here will end this?"
For the first time, the man looked straight at me. His gaze didn't waver. But it was the look of someone who knew my name. At the very least, not a man who had lived only as a market runner.
I spoke even lower.
"Who ordered you?"
A brief silence. Then he swallowed a blood-tinged breath and opened his mouth.
"…You're already too late."
The room went very still. I didn't change my expression.
"Too late for what."
He twisted the corner of his mouth.
"This place is bait."
Dein's grip tightened. The Grand Duchess's eyes went cold and still. I turned the words over. If the waterway office was bait, it meant that while we were held here, the real move was happening somewhere else.
That was the moment. A very low vibration rose from beneath the office floor.
Grrrk.
The Grand Duchess's head snapped up.
"…That didn't come from the lever I touched."
The Imperial Princess snapped a short order.
"Back!"
But it was already too late. One of the floor stones at the rear of the office dropped away, and through the gap black water surged up. A mass close to pure contamination. The stench alone was enough to choke the breath from your lungs.
I shouted on instinct.
"The sluice!"
The Grand Duchess's ice threads raced across the floor first, and the Imperial Princess's gold light stabbed in behind them. But the black water had already split — not into one stream, but three. One toward the sluice, one toward the outer valley, and the last toward the underground drainage line that ran in the direction of the main keep.
"Damn it."
I clenched my teeth and ran for the sluice lever. I couldn't grip it with the bandaged hand. I tried to pull with my left, but the stiff, seized metal wouldn't budge for a hand I didn't normally use.
Then my father's voice came from behind.
"Move."
I lifted my head. I didn't know when he'd arrived, but Father stood in the doorway of the office. Behind him were Kyle and two soldiers from the keep. Without hesitation Father stepped in beside me and seized the lever with both hands. Force gathered in the corded backs of his hands, and the metal groaned like bone grinding on bone.
Krrrk.
The lever turned halfway. The Grand Duchess's ice sealed the underground channel into the gap, and the Imperial Princess's gold light punched straight through the center of the black stream racing toward the keep. The black sludge twisted and plastered itself against the wall.
I immediately hauled on the secondary lock on the opposite side. The iron ring slipped in my palm, but this time I didn't let go.
Clack.
The sluice locked fully shut. In an instant the water-sound that had filled the room cut off. The black water had risen to about half the floor; unable to advance any farther, it shuddered in place.
The Grand Duchess let out a low breath.
"…We've stopped it."
The Imperial Princess, without withdrawing her gold light, looked down at the pinned man.
"That word 'bait' — you don't get a chance to take it back."
For the first time, the man's face crumbled. The look of someone who had just realized his calculations had gone wrong.
I steadied my roughened breathing and leaned against the wall. We had blocked the channel flowing toward the keep. But this wasn't the end. That man still had to talk. And inside the keep itself, there were still lines we hadn't touched.
Father released the lever and glanced at me.
"You were right."
I couldn't even manage a hollow laugh.
"We're only halfway done."
Father answered briefly.
"Yes. Which means from here on, we make him open his mouth — and quickly."
Outside, the wind slammed hard once. Cold air rushed in through the gap in the collapsed roof, and a single ember in the oil lamp went out. The darkness deepened.