But it was not inviting them to rush.
Gu Yan stood still for one breath after the faded line of writing vanished above the stone table. The newly opened descent at the far wall remained narrow, dark, and quiet. It looked less like a proper path and more like something the buried line had reluctantly exposed because it had judged them useful enough to continue and foolish enough to die.
Pei Zhen looked from the slit of darkness to the table, then back again. After a moment, Pei Zhen said, "I dislike places that warn us and open anyway."
Gu Yan kept his eyes on the descent and answered, "That is because this place expects obedience, not agreement."
Pei Zhen let out a tired breath. "That is not better."
Another muted knock came through the wall behind them.
Not loud.
Not random.
Measured.
Lu Qingshan was still there, still testing, still listening.
Pei Zhen turned his head slightly toward the sound before muttering, "He is going to keep learning until he reaches our side of the wall."
Without wasting more words, Gu Yan moved toward the narrow descent and said, "Then we move before he does."
Pei Zhen followed, though not happily.
The passage beyond the service gallery dropped more steeply than the stair before it. The ash underfoot was finer here, and the walls were warmer. Not violently so, but enough to make the air feel close and dry. Old black brick gave way in places to fitted dark stone engraved with shallow line-marks, the kind used for measurement rather than decoration.
That mattered.
The service gallery had not been the destination.
It had been a checkpoint.
This route below was for the thing that came after.
Gu Yan descended first. His body still ached from the earlier correction and from the settling medicine he had swallowed. The newly aligned line through his torso had not become comfortable. It had become clear. Every step told him where the body still resisted and where it no longer lied.
That clarity was valuable.
It was also cruel.
Behind him, Pei Zhen moved more carefully than usual. After the passage tightened and forced them into single file again, Pei Zhen spoke in a lower voice and said, "If this next room asks you to suffer for improvement again, I will begin resenting your destiny personally."
Gu Yan did not turn when he replied, "You already resent it."
Pei Zhen answered at once, "Yes, but I can still deepen the feeling."
The route bent once, then opened.
Gu Yan stopped in the threshold and immediately understood the purpose of the chamber beyond.
This room was not built to push a body forward.
It was built to keep it from collapsing backward.
Four waist-high stone platforms stood in a square around a shallow basin carved into the floor. Each platform bore worn foot outlines, hand placements, and long engraved body-lines that ran from heel to spine to shoulder. Along the walls hung racks of dark metal braces, some broken, some intact. The far wall held narrow drawers and stone recesses, and above them were three lines of stamped script worn almost smooth by age.
The whole chamber felt severe in a different way than the rooms above.
No heat-heavy pressure.
No great spectacle.
Only the cold patience of a place meant to test whether correction had truly taken hold.
Pei Zhen stepped in beside Gu Yan, looked at the platforms, and then looked at the metal braces along the wall. After a long breath, Pei Zhen said, "This room looks like it enjoys proving people wrong."
"It does," Gu Yan said quietly.
Pei Zhen glanced sideways at him. "You sound as if you respect that."
"I do."
"That is deeply troubling."
A faint pulse passed through the floor.
One of the four platforms lit from within.
Not brightly.
Just enough for a thin red line to awaken along the engraved path.
Gu Yan approached the nearest one.
The line on the platform remained dim until he stepped onto the worn foot marks. The instant his weight settled, the red line ran from heel to knee, from knee to hip, from hip to spine—
and then faltered beneath the lower ribs.
Gu Yan saw it.
So did Pei Zhen.
Standing to one side, Pei Zhen folded his arms and said, "Your body is still betraying you there."
"Yes," Gu Yan answered.
He shifted his weight very slightly and adjusted the angle of his shoulders.
The line changed.
When the chest led first, the red path shook. When the back and spine carried first, the line stabilized.
Pei Zhen clicked his tongue softly and said, "So the room is not measuring strength. It is measuring whether your body learned what the chamber above forced into it."
Gu Yan stepped off the platform and answered, "Yes."
That answer made Pei Zhen quieter than usual.
It was one thing to gain improvement under pressure.
It was another thing entirely to discover whether the body had truly accepted it.
Gu Yan moved to the wall racks and took down one of the dark metal braces. It was light, flexible, and colder than the room around it. Thin etched markings ran along its inside edge.
Not weapon marks.
Body marks.
The brace had been made to hold a corrected line in place after treatment.
Pei Zhen looked at the brace, then at the platform, and then at Gu Yan with visible suspicion. After a moment, Pei Zhen said, "No."
Gu Yan did not ask what he meant. He only set the brace down beside the platform.
Pei Zhen pointed at it and said, "No. I know that face. I know that room. I know that you are about to do something extremely unpleasant in the name of long-term benefit."
"That is because you are finally learning," Gu Yan said.
Pei Zhen stared at him for one breath, then muttered, "I hate that answer more every time."
Another knock came through the wall behind them.
Closer now.
Still measured.
Still patient.
Lu Qingshan had not stopped. He was simply advancing with less noise.
That settled the matter.
Gu Yan crossed to the drawer wall and pulled the first narrow drawer open.
Inside lay folded measurement slips, two clay weights, and a sealed stone cup.
He opened the cup.
Inside was a pale paste shot through with fine silver grit.
Pei Zhen recoiled half a step at the smell and said, "That is not medicine. That is a threat."
"It is medicine," Gu Yan corrected.
"That does not contradict me."
Gu Yan examined the paste carefully. It was not the same as the settling pellet from the service gallery. This compound was meant for external use. The scent told him enough: powdered bone mineral, cooling ash residue, blood-binding herbs, and something meant to contract and hold.
It was for fixing a corrected route long enough that the body had no choice but to accept it.
Gu Yan set the cup down beside the brace.
Watching him do that, Pei Zhen rubbed his forehead once and asked, "How much pain are you about to choose?"
"As much as the room says is necessary," Gu Yan answered.
"That is a horrifying way to live."
Gu Yan ignored the complaint and unfolded one of the measurement slips. The slip was old, but the body-lines matched what the platform had just shown him: shoulder angle, spinal alignment, lower rib path, side-body load, and force transfer through the back.
He looked at Pei Zhen and said, "Read this against me."
Pei Zhen blinked. "You trust me with that?"
Gu Yan stepped back onto the platform and said, "I trust that you do not want me crippled before we reach the lower hall."
That made Pei Zhen snort despite himself. Then, with far more seriousness than his tone usually suggested, Pei Zhen moved to the platform's side and studied both the slip and Gu Yan's body.
Pei Zhen pointed first at Gu Yan's left shoulder and said, "Lower that."
Gu Yan adjusted.
Pei Zhen shook his head and corrected him. "No. Not like that. Stop correcting from the front. Set the back first, then let the shoulder fall into place."
Gu Yan followed the instruction.
The red line beneath the platform steadied slightly.
Pei Zhen leaned closer, compared the slip to the lower torso line, and then said, "Better. Now shift a little more weight into the rear leg. Not much."
Gu Yan made the change.
The red line beneath the lower ribs stopped fluttering and held.
Pei Zhen let out a slow breath and said, "There. That is the least wrong it has looked."
"That will do," Gu Yan said.
Pei Zhen immediately gave him a sharp look. "That phrase should not make me this nervous."
Gu Yan dipped two fingers into the pale paste and spread a narrow band of it along the unstable line beneath the ribs and across the side of the torso where the correction from above still had not fully settled.
The paste bit with cold.
Real cold.
Not absence of heat, but active constriction.
That made sense.
The previous chamber had corrected with heat and force. This one preserved with pressure and contraction.
Gu Yan placed the first brace against the treated line.
It locked in with a faint click.
Then he placed the second lower, just where the emerging line toward Bone still fought the old shape of his body.
The platform answered at once.
The red path beneath his feet lit more sharply, then ran upward through his frame. The braces tightened—not enough to damage, but enough to force the corrected route to remain the easiest path.
Pain followed a breath later.
Deep, sharp, and immediate.
Gu Yan's whole torso wanted to recoil.
The old body-shape wanted to return.
The braces denied it.
Pei Zhen watched the shift in his face and said, "That expression is exactly why I objected."
Breathing through the back as steadily as he could, Gu Yan answered, "It is working."
Pei Zhen's mouth flattened. "Your standards remain diseased."
The pressure held.
Not long.
Just long enough.
That was the chamber's real value. It did not grant power. It forced commitment. Either the body held the new path, or it revealed itself too weak to keep what it had been given.
When the braces finally loosened and Gu Yan stepped down from the platform, sweat had gathered along his neck and back. The pain under the ribs had not vanished, but it had narrowed. The false spread across the front of the torso felt weaker than before.
Not gone.
Better.
Watching him carefully, Pei Zhen asked, "Can you fight like that?"
"Badly," Gu Yan admitted. Then, after rolling one shoulder and feeling the response, he added, "But better than before."
Pei Zhen let out a breath through his nose. "That should not count as reassurance, but apparently it will."
A new sound came from the right side of the chamber.
Not from the wall behind them this time.
From deeper beneath the floor and the half-sealed side channel cut into the stone beyond the brace racks.
Both men turned.
Fine ash slipped from the crack there.
Then the crack shuddered once, as if something below had forced pressure upward through a blocked vein.
Pei Zhen's expression hardened again. Keeping his voice low, he asked, "Alive?"
Gu Yan crossed to the crack and crouched. He placed his palm against the stone and listened through it with more than ordinary qi-sense. The correction chambers had already sharpened something in him—an ugly, useful sensitivity to old pressure, buried heat, and the shape of stressed stone.
After one breath, he shook his head.
"No," Gu Yan said. Then, after listening again, he added, "Not alive. The line below is venting through a blocked section."
Pei Zhen came to stand beside him and looked toward the crack. "So the path deeper is still there."
"Yes."
"Stable?"
"No."
Pei Zhen exhaled. "At least you remain consistent."
Gu Yan pulled out the treated hide map from the service gallery and compared it to the chamber's layout. The route toward Root Hall had clearly been damaged, but the pressure in the crack suggested some lower bypass still survived—something narrow, ugly, and not meant for formal passage.
He rolled the map shut again.
Pei Zhen looked from the crack to the braces still lying near the platform, then back to Gu Yan. After a pause, Pei Zhen said, "Say the ugly answer out loud."
Gu Yan did not soften it. "One more correction before the root descent."
Pei Zhen closed his eyes for a moment. "I knew I hated this room for a reason."
Then came the sound both men had been expecting.
Behind them, somewhere near the service gallery wall, stone shifted with a deeper scrape than before.
Lu Qingshan had found another seam.
This time, even the old chamber seemed to tense around the sound.