They returned to the Broken Spine at dusk.
The mountain had changed its quality again with the shift of light — morning had been clean and purposeful, afternoon had been workmanlike, and now evening brought something that was neither. The ridgeline in the low orange light looked less like a geological formation and more like a threshold, which Hungan supposed it was, had always been, and which the light simply made honest.
Shao Peng came with him. Cao Renfeng stayed at camp with the day's documentation, not because he was excluded but because he had made the quiet calculation that his presence at the ridge during Hungan's deeper reading was not necessary and that the documentation of what Hungan reported afterward would be more useful than his observation of the reading itself. This was the kind of judgment Cao Renfeng made consistently and without announcement — the precise assessment of where his presence added something and where it did not, and the absence of ego about the distinction.
Shao Peng came because Hungan had not said not to, and because Shao Peng had a different function in these moments than Cao Renfeng did. Cao Renfeng recorded. Shao Peng witnessed. The difference was subtle and neither of them had articulated it but both of them understood it, and Hungan understood it too — that having someone present who was not recording but simply there, attending, was its own form of support that had nothing to do with documentation or measurement and everything to do with the fact that some things should not be done entirely alone.
They reached the seventh gap in the ridge where Hungan had sat the previous day.
The stone was still faintly warm from the afternoon sun, which had no bearing on anything but was a pleasant fact. Hungan sat and placed his palms against the rock.
Shao Peng sat on a nearby stone and looked at the sky.
Hungan went back into the record.
The first two layers were familiar now — the geographical map, the observational records — and he moved through them with the ease of a second visit, noting details he had not caught the first time. Bai Songhe's geographical map covered a region significantly larger than Jiuling's current administrative boundaries, which meant either the boundaries had changed in two centuries or Bai Songhe had traveled considerably further than the eastern region. Probably both. The observational records showed a practitioner who had grown more precise over time — the earlier entries had the quality of someone learning their own methodology, and the later ones had the quality of someone who had learned it so thoroughly it had become invisible, the way a skilled calligrapher's grip on the brush becomes invisible in the quality of the strokes.
Then the personal layer.
He settled into it differently this time. Not with the careful distance of a first approach but with the acknowledgment that he was reading something that had been left for whoever could reach it, and that he could reach it, and that the appropriate response to that fact was attention rather than apology.
Bai Songhe had been born in the eastern region. He had discovered his capability for Vessel work accidentally, at nineteen, when he had stumbled into a boundary location during a storm and found himself briefly in the perpendicular space of a Vessel without intending to enter it. Most practitioners who encountered Vessel space unexpectedly found it disorienting to the point of distress. Bai Songhe had found it clarifying. He had stayed for three hours and emerged with a precise sense of what the space was and what it related to, which he then spent the next decade trying to understand in formal terms before concluding that the formal terms available to him were inadequate and beginning to develop his own.
He had been, Hungan understood, a person who was comfortable in the gap between what was known and what was not — comfortable not in the sense of indifferent to the uncertainty but in the sense of finding the gap genuinely interesting rather than threatening. This was a rare quality. Most people, encountering the boundary of what was known, wanted to either fill it quickly or retreat from it quickly. Bai Songhe had been content to stand in the gap and look carefully at its shape.
The doctrine revision had begun when Bai Songhe was twenty-seven.
The record described it without bitterness, which Hungan found more affecting than bitterness would have been. Bai Songhe had understood the revision as something that had its own logic — not correct logic, in his assessment, but comprehensible logic. The revision was driven by practitioners who found the theoretical complexity of Vessel work destabilizing to the broader cultivation framework. If Vessel space existed perpendicular to the main layer, and if the Vessels connected to something beyond the world, then the main layer was not the totality of existence, and if it was not the totality of existence, then the cultivation frameworks built on the assumption of its totality required fundamental revision. This was true. The revision's authors had chosen to address this problem by removing Vessel work from the framework rather than revising the framework to accommodate it.
Bai Songhe had understood their reasoning. He had disagreed with their conclusion. He had continued his work quietly, outside the formal structure, storing what he found in places the formal structure could not reach.
The deeper personal layer — the part Hungan had not read the previous day — began at the point in Bai Songhe's life when the censure became serious.
He had been thirty years old.
The record here was different in texture from the earlier sections. The earlier sections had been composed with the care of a person writing for an unknown future reader — organized, deliberate, shaped for comprehension. This section had been written under time pressure. Not panic — Bai Songhe was not a person given to panic, the record made this clear — but urgency. The urgency of someone who had a limited window to encode everything that mattered and was making rapid decisions about priority.
He had reached his thirty-first access point three weeks before the record in the ridge was completed.
The thirty-first point.
Hungan settled his attention more carefully.
The thirty-first point, in Bai Songhe's record, was located at the convergence of three boundary formations — two point locations and one linear formation shorter than the Broken Spine but similarly structured. The convergence created something that Bai Songhe described as a focal point, a place where the perpendicular pressure of Vessel space was concentrated by the intersection of multiple boundary lines into a single location of unusual intensity.
At ordinary access points, the boundary between the world layer and Vessel space was clear. At the thirty-first point, Bai Songhe had found that the boundary was not entirely clear. Something on the far side of the Vessel boundary at this location was present in a way that something on the far side of a boundary should not be able to be present — not inside the Vessel space, not inside the world layer, but at the boundary itself, occupying the threshold in a way that was neither entrance nor exit but simply: there.
Bai Songhe had reached into the boundary carefully, the way Hungan had reached toward the signal at the seventh point — close enough to understand the quality, not close enough to commit to the encounter.
What he had found was a frequency.
Not the external signal from beyond the planet — Bai Songhe had not known about that signal. What he had found was a frequency that existed in the threshold itself, not coming from outside and not originating inside, but native to the in-between. A frequency that the threshold generated from the convergence of multiple boundary formations meeting at a single point. Something that had no source, because it was itself the source — produced by the structural fact of several perpendicular boundaries meeting, the way a note is produced by the meeting of two vibrating surfaces and belongs to neither of them individually.
Bai Songhe had described it as the sound a door makes when it opens.
Not the door opening. The sound. The frequency that existed only in the moment of transition between closed and open, belonging to neither state.
He had composed a response to it. Had stored the response in the ninth access point's boundary — the closest stable boundary to the thirty-first point that was not the convergence itself — intending to return to the convergence and attempt transmission. Had been prevented from returning by the escalation of formal censure into something that required him to leave the region entirely.
The record ended there.
The final entry was brief. Bai Songhe had written it in the ridge at the Broken Spine on his last night in the eastern region, encoding it at depth rather than on the surface because the surface layers were for whoever eventually came and the deep layer was for himself — a private accounting, a record of what he had found and what he had been unable to finish and what he hoped the finding was worth.
He had written: the threshold frequency is an answer to a question I do not know how to ask. Perhaps the question is larger than one practitioner's capability. Perhaps it requires conditions that do not exist yet. I leave the response in the ninth point for whoever arrives with the right frequency and the right question and the right willingness to stand at a threshold and not rush through it.
Then, in smaller script below, as though added after a moment of stillness:
I hope they are not alone.
Hungan sat with this for a long time.
The dusk had deepened around him. Shao Peng was still on his stone, looking at the sky, which now held stars rather than light. He had not moved or spoken since they arrived. His presence was steady and uncomplicated and exactly what it was supposed to be.
Hungan withdrew from the record in stages, closing each layer behind him with care.
He sat in the mountain dark for a moment longer.
Then he said, "Shao Peng."
"Here," Shao Peng said, which was the right answer.
"Bai Songhe hoped the person who found his work would not be alone." Hungan looked at the ridgeline against the stars. "He would have found that correctly predicted, I think."
Shao Peng was quiet for a moment. "What did you find in the deeper layer?"
Hungan told him.
He told him carefully and completely, the way he had learned to brief the expedition team — not filtering for what seemed important and discarding what seemed peripheral, because the history of this work had shown repeatedly that what seemed peripheral often was not, and that Cao Renfeng's documentation was only as useful as the accuracy of what went into it. He described Bai Songhe's life in the broad strokes that were relevant. He described the thirty-first point — the convergence, the threshold frequency, the sound a door makes when it opens. He described the unsent response stored in the ninth point's boundary. He described the final entry in the personal layer, including the small addition at the bottom.
Shao Peng listened without interrupting.
When Hungan finished, Shao Peng sat in silence for a moment, looking at the ridgeline.
"He Daomin's anomaly at the thirty-first point," he said finally. "The model flags it as an unnamed direction. If the threshold frequency is native to the convergence — if it's produced by the intersection itself rather than coming from outside — then He Daomin's model would register it as a direction without a source. Something pointing toward a location that doesn't correspond to any known vector."
"Yes," Hungan said.
"Because it's not pointing toward anywhere. It's pointing toward the threshold itself. The between."
"Yes."
Shao Peng nodded slowly. "When we reach the thirty-first point — you're going to respond. To the threshold frequency."
"I'm going to read Bai Songhe's unsent response first," Hungan said. "And then I'm going to decide."
"What would change the decision?"
Hungan considered this honestly. "If his response is already complete. If what he composed two hundred years ago is sufficient and just needed someone with the right frequency to transmit it." He paused. "Or if the conditions have changed enough that his response is no longer accurate."
"And if they've changed?"
"Then I write a new one." Hungan stood from the stone. "With what we've found across thirty-one points that he never reached."
He walked back toward camp, his footsteps quiet on the mountain path, and Shao Peng fell into step beside him without discussion, and Mage was at his left shoulder in the particular way that meant something had shifted in how the situation was understood — not the situation itself, not yet, but the understanding of it, which sometimes preceded the situation's change by exactly as long as it took to close the distance between where you were and where the thing was waiting.