The four-beat pattern became its own project.
He had the extract Peva had made — clean, isolated, the full frequency data stripped of the surrounding recording. He had the precise timing values: the first beat was the anchor, established at a frequency that corresponded to no particular musical pitch but had the quality of a root note, a starting point. The second beat was faster, higher in frequency by a factor that was specific enough to be intentional. The third dropped back, below the anchor, in the frequency range that Peva had identified as matching the Harrow block's column resonance. The fourth was a return to the anchor, but offset — the same pitch, different timing, delayed by a precise fractional amount that changed the relationship between the return and the beginning.
He spent a week with it. He tried the pattern on his rods, replicating the frequency values and timing as precisely as he could with his cells adjusted to minimum output. He wrote it out in notation shorthand. He reversed it, inverted it, shifted the starting point from beat one to beat three to beat two.
Nothing resolved into meaning.
He was on his second week when Sera Ondas arrived at the training space on what was supposed to be his morning and found him sitting in the middle of the floor, rods in hand, the secondary chip on the ground in front of him, working the four-beat sequence for what he estimated was the hundredth time.
She stopped in the doorway. She assessed the situation. She came in and sat against the far wall.
"You've been doing that for two hours," she said.
He looked up. He hadn't heard her come in, which was a failure of attention he noted without pleasure. "Your session isn't until even-cycle morning."
"This is even-cycle morning." She set down her tessaviol case. "It's also your session. I had a conflict yesterday and rescheduled." She looked at the chip on the floor. "What is that?"
He considered how to answer. He thought about Joss: don't tell anyone else. He thought about what Peva had said: I wasn't here.
He thought about the fact that Sera had identified Seren's methodology in his technique, which meant she had access to Academy archives, which meant she might know things about rhythmic ciphers that he was never going to find on his own in the Lower Tiers.
"It's a rhythm pattern I'm trying to decode," he said. "Four beats. I think it's a cipher but I can't find the key."
She looked at him for a moment. Then she walked to the center of the floor and sat down across from the chip. She had the careful attention of someone who approached problems methodically. "Play it for me."
He played it — the four beats through his left-hand rod at minimum output, as close to the recorded values as he could reproduce.
Sera listened. Her head tilted slightly. "Again," she said.
He played it again.
She was quiet for a moment. Then: "The third beat is at four-seventeen Hz."
He checked his cell output reading. "Four seventeen point three."
"That's the resonance harmonic of the Spire's primary support column. The one that runs through Tiers Three to Seven on the eastern face." She was looking at his rod, not at him. "It's specific. It's not a standard performance frequency."
"I know."
"The fourth beat's timing offset." She reached over and, without asking, adjusted the chip on the ground to a better angle relative to her. "The fractional delay. If this is a cipher, the offset is either a positional key or a directional marker."
"I've been treating it as positional," Kael said.
"Directional is more interesting." She looked up at him. "In some of the older Resonance Academy cipher systems — and I want to be clear that I'm working from historical documentation I've read, not practical training — a directional marker would indicate a physical location. The offset encodes a bearing, and the frequencies encode reference points."
Kael stared at her.
"Where did you get this?" she said. The question was neutral, not demanding. Academic.
He made a decision. "From a recording," he said. "Embedded below the consumer reproduction threshold. I had it analyzed by someone who works in acoustic engineering. The frequency signature is consistent with—" He paused. "With a specific Rhythmist from the pre-restriction archive."
Sera looked at him for a long moment. Her expression didn't change dramatically, but there was a quality of recalibration to it, the same thing he'd seen when she identified his technique.
"Seren's archive was restricted eleven years ago," she said carefully.
"Yes."
"The night of his final concert."
"Yes."
She sat back. She was working through something, he could see it. "His techniques aren't just in the Academy archive," she said slowly. "Some of the earliest documentation — the interviews, the methodology notes — there's material in there that was never publicly released. Not just restricted but held in a specific sub-archive with different access controls." She looked at him. "I've seen references to it but I've never been given access. The sub-archive has a clearance level that's above Academy faculty."
"Why would a musician's methodology have that level of clearance?"
"I've wondered." She looked at the chip. "I've been wondering for two years." She glanced up at him. "If what you're saying is correct — if this pattern is a cipher from Seren, embedded in a recording made at his last concert and left to be found by someone with the right equipment — then whatever it's pointing to, the city's authority considers it significant enough to bury the context."
The training space was very quiet. The resonance-treated walls absorbed even the ambient noise of the Spire's machinery, leaving a silence that felt deliberate.
"I need to understand the directional interpretation," Kael said.
"I can try to work through the calculation. I'll need the precise frequency values and the timing data." She reached out her hand.
He passed her the secondary chip.
She looked at it, then at him. "You don't know me," she said. "We've been in the same space four times."
"You've been in Seren's restricted sub-archive documentation. You know things about his methodology that most people don't." He met her gaze. "And you came in here on a different schedule and found me working on this instead of asking me to stop."
She was quiet for a moment. Then she put the chip in her jacket pocket.
"I'll need three days," she said. "And you should know that whatever this is pointing to — if the cipher system I'm thinking of is correct — it's not going to be something simple." She picked up her tessaviol case and stood. "Nothing Seren did was simple."
She went to her side of the space and began her warmup. Kael sat for a moment and then did the same.
They worked in silence, and the treated walls held everything in.