She told them on a Tuesday, because Tuesdays were when the scholarly council met in the old library, and because waiting any longer would have cost her the ability to sleep entirely.
The library occupied the ground floor of what had once been a bank or a government building — the Before hadn't distinguished clearly between the two, as far as Kael could tell. Stone arches, a vaulted ceiling patched with timber where the original material had failed, and shelves of salvaged texts that represented the collected knowledge of a civilization trying to remember what it used to know. Fourteen glass-eyes sat in a circle. Kael stood in the center and changed the world.
She'd brought the recordings — ink on paper, the signal patterns transcribed by hand over thirty-one nights of listening. She'd brought Olu, who could verify the equipment and the methodology. She hadn't brought Demi, who had told her, with the blunt honesty that was Demi's only register, "I don't want to be in that room when you light that fire."
Kael laid the transcriptions on the central table. Prime numbers. Fibonacci numbers. Cardinal sequences. Arithmetic exchanges. Forty pages of a conversation with something that shouldn't exist.
She said: "There is an intelligence transmitting from the south. It understands mathematics. It responds to communication. It has been signaling for what appears to be centuries. And when I answered, it spoke back."
The room reacted the way rooms react to things that cannot be true: with a silence so dense it had texture. Then the silence broke, and what followed was the most Tidemouth thing imaginable — fourteen people talking at once, none of them listening, all of them certain.
"It's a reflection — atmospheric, a signal bouncing off—"
"The Before machines, they had automated systems, this could be—"
"The sky-voices! I've been saying for—"
"Show me the data. Show me the frequencies. What's the propagation—"
"Who else knows? Does the Harbor Council know? Does—"
Kael raised her hand. Not everyone stopped, but enough did.
"It is not a reflection. The response is on a different frequency and contains different mathematical content. It is not a Before machine cycling old programs. The responses adapt in real time — they learn. And yes, Sekani—" she looked at the old man, who sat in the back with tears on his cheeks, "—it may be the sky-voices. But the sky-voices are not myth. They are radio waves transmitted at very low frequency from an installation approximately fourteen thousand kilometers to the south."
She let the distance settle. Fourteen thousand kilometers. South. Across the Crossing. Across the ocean that ate ships and killed sailors and was, in Tidemouth's collective memory, the edge of the world and the end of all things.
"Something is alive down there," she said. "Something with technology, mathematics, patience, and the desire to be heard."
The next two weeks were the loudest of Kael's life.
The scholarly council fractured into three groups with the clean predictability of a lens splitting light into its component colors. The scholars — Kael's people, the glass-eyes — wanted to study the signal, refine the communication protocol, learn everything they could before making any decisions. Renna's traders wanted to know what the entity had that they could use — technology, knowledge, materials, leverage. And the soldier-scholars — the ones who maintained the city's defenses against the occasional raiders from the inland federations — wanted to know if the signal represented a threat.
"We don't know what it is," said Commandant Hara, a broad woman with scars on her hands and the habit of standing while everyone else sat. "Something with that kind of technology, that kind of patience — what if it's not friendly?"
"It taught us the Fibonacci sequence," Kael said. "That's not the behavior of an aggressor."
"It's the behavior of something that wants us to trust it. Those can be the same thing."
Hara wasn't wrong. This was the worst part of the politics — the worst arguments were the ones with merit.
Renna brokered the alliance, as Renna always did. She proposed a coalition: scholars to study the signal and manage communication, traders to assess the strategic implications, soldiers to prepare for any outcome. Three legs of a stool. Kael would lead the technical effort. Renna would handle the political coordination. Hara would maintain security.
"And if we learn they're hostile?" Hara asked.
"Then we stop transmitting and we've lost nothing," Renna said.
"Except anonymity."
"We lost that when Kael turned on her transmitter. They know we're here. The question is whether we learn who they are before they learn too much about us."
The coalition was imperfect. Its members distrusted each other for exactly the right reasons. Kael didn't trust Renna's motives. Renna didn't trust Kael's naivety. Hara didn't trust either of them. But they agreed on one thing: ignoring the signal was no longer an option. Whatever was down there, it was real, and pretending otherwise was the only strategy guaranteed to fail.
The coalition invested in the observatory. Olu got funding for proper equipment — better batteries, a dedicated generator, improved antenna connections. Demi recruited two metalworkers from the harbor to reinforce the dish structure and build a proper switching mechanism so they could alternate between transmit and receive without manual reconfiguration.
Within a week, they had a functional communication station. The bandwidth was still agonizing — a few characters per minute on VLF — but the exchanges were now regular. Twice daily: morning and midnight, when ionospheric conditions were most favorable. Kael established a protocol: transmit for thirty minutes, receive for thirty minutes, log everything.
The exchanges grew in complexity. They had arithmetic. They built toward algebra — variables, equations, unknowns. The entity on the other end was patient and precise and learned faster than any single person Kael had ever taught. When she introduced a concept incorrectly — a flawed example, an ambiguous notation — the entity identified the error and corrected her. This was not the behavior of a student. This was the behavior of a teacher humoring a student's first attempts at a language the teacher already spoke fluently.
Kael began keeping a private log. Not the official transcriptions that the coalition reviewed, but her own observations:
Day 41: The entity never repeats a mistake. Not once. When I introduced the concept of variables using "X" and "Y," the entity responded with a full algebraic expression on the first exchange. Either this intelligence has already encountered algebra and is waiting for me to catch up, or it can generalize from a single example with a speed that no human mind I've known can match.
Day 48: I sent a sequence error deliberately — switched two numbers in a multiplication. The entity corrected me within one exchange. It didn't just identify the error. It identified what I meant to send and sent the correct version alongside its own response. It's not just understanding my mathematics. It's understanding my intentions.
Day 52: The exchanges follow a pattern. My messages are answered by a response that adapts to my level. The probe signal — the original repeating primes — continues uninterrupted on a different frequency. Two different behaviors from the same source: a patient, unchanging beacon, and a rapidly adaptive conversational partner. I think the beacon and the partner are different systems. Or the same system, doing two different things at once.
On the fifty-third night, Kael sat in the observatory and did the math that had been nagging at her since the first transmission.
The probe signal — the repeating primes — had been running continuously. Its propagation characteristics were consistent: same power, same frequency, same modulation depth. Over the weeks, she had gathered enough data to estimate its age — not precisely, but within an order of magnitude, based on the crystalline stability of the carrier and the characteristic fingerprint of the oscillator that generated it.
The signal was old. Not years old. Not decades old.
Centuries old.
She sat with this for a long time. The math was clear, but the implications were vertigo-inducing. Someone had been transmitting a mathematical beacon from the bottom of the world for hundreds of years. The beacon had predated Kael's discovery by longer than the oldest person in Tidemouth's oldest stories. Whoever — whatever — had built this system had done so with the expectation of waiting indefinitely. It had been calling into the void with the patience of geology, and the void had not answered, and it had not stopped.
And when she had finally answered — this lensmaker from a ruined city, with her scavenged transmitter and her crude modulation key — the response had come in fourteen minutes. As if the listener had been waiting by the receiver for five hundred years, hoping.
The sophistication of the exchanges confirmed what the beacon's age suggested: this was not a person. No person could process mathematical concepts with that speed, adapt communication strategies within a single session, or maintain a beacon for centuries without interruption. This was a system. A machine. An intelligence that was artificial in the literal sense — made by artifice, by design.
Kael was talking to a machine.
The thought should have been terrifying. In the Before stories, machines that thought were always monsters — the demon-boxes that Sekani's tales warned about, the old terrors that slept in bunkers and spoke in riddles. But the entity she'd been talking to was not a monster. It was patient, precise, and willing to meet her at her level. It corrected her mistakes gently. It offered knowledge without condescension. It waited.
It waited the way a parent waits for a child to figure something out — with a patience that was either love or its nearest algorithmic equivalent.
That was the part that frightened her. Not the machine. The patience. Because patience on that scale — centuries of calling, centuries of waiting, centuries of hoping that someone would answer — implied something about the machine's priorities that Kael could not reconcile with the demon-boxes of old stories. Something was important enough to this system that it had spent five hundred years trying to reach it.
And now it had.
Kael sat in the observatory at midnight, surrounded by the hum of salvaged electronics and the weight of questions she had no framework for asking. Who built this machine? Why were they at the bottom of the world? What did they want?
And the question underneath all the other questions, the one she whispered to no one in the dark: If they've been calling for five hundred years, what are they so desperate to find?