A signal that shouldn't exist. Then: silence.

The bridge is empty except for you, the way it is every night during third watch, and the static from the external receivers hasn't changed in weeks — until now.

It starts as a single tone, too clean to be noise. Then a second, exactly four seconds later. Then a third. A pattern, not interference.

You run the frequency through the filter twice, because you don't trust yourself. The pattern holds: an old distress protocol, struck from the active catalogue forty years ago, because nobody carries equipment that transmits it anymore.

The source sits in a sector the charts list as empty. No outpost, no wreck, no route anyone has ever logged through here. For eleven days your ship has been the only mass in this volume large enough to throw an echo.

You don't wake anyone. Not yet. Instead you listen, headphone pressed hard against one ear, while the bridge sits around you in its usual half-dark, only the status bars pulsing quietly.

The pattern runs for seven minutes, exactly identical each time, with no deviation that would suggest a malfunction. A person recorded this, or a machine imitating a person with real precision.

Then, in the middle of the eighth repeat, it cuts off.

Not fading. Not distorted. Simply gone, between one tone and the next, and the silence left behind is louder than any alarm this ship has ever raised.

The long-range scanner needs nine minutes for a single confirmation, and you count every one of them while outside nothing but stars sit exactly where they have sat for eleven days.

The result: an object, compact, not much larger than a lifepod, no drive signature, no heat bloom that would suggest active systems. It isn't drifting with the debris field the charts say shouldn't even exist out here — it moves independently of it, on a path too regular to be chance.

You check the distance against your course. A diversion there and back costs four days, more than your return fuel margin allows without a safety cut. The last unauthorised course change was eighteen months ago, and there was a procedure afterward that nobody on board wants repeated.

On the second monitor the pattern keeps looping, because you never turned it off. Seven minutes, cutoff, silence. Seven minutes, cutoff, silence.

You think about the age of the protocol. Forty years. Whoever originally sent it isn't sending anymore — the object is just still doing it, like a recording replaying itself long after anyone stopped listening.

Or somebody is still listening, and waiting for someone, finally, to answer.

The call button for the captain's cabin sits under your hand. So does the channel you could use to send a reply yourself, unauthorised, before anyone else on board even knows the night turned into something else.

The captain looks at the pattern once, then again, and doesn't say a word the whole time.

"Forty years old," she says eventually. Not a question. She recognised the protocol as fast as you did.

She changes the course herself, without handing bridge control back to you — a four-day diversion she logs under a single word: bearing.

Yara, the engineer, arrives on the bridge an hour later, woken by the drive telemetry rather than any alarm. The three of you are awake together now, more people than in the last eleven days combined.

"Full silence past a hundred kilometres," the captain orders. "No active sensors, no radio, passive only. If something out there has been transmitting for forty years, I don't want us to be the first thing that hails it."

You spend the last six hours of the approach almost without speaking. The ship goes quieter console by console, until only life support and passive sensors are running and even the coffee machine stays cold on the captain's order.

At fifty kilometres the object appears visually for the first time, a grey point barely distinct from the starfield behind it.

At twenty kilometres you can see it isn't a lifepod.

It has a shape that matches no hull design any of you know, and an opening on one side too regular to be damage.

Then, without anyone on board transmitting anything, the pattern on your receiver answers — for the first time in hours. It has changed.

You record without transmitting, and that's exactly what makes it unsettling: the pattern changes anyway.

The loop that stayed perfectly identical for forty years now carries a new segment at the end, three seconds long, absent from every recording taken in the first hours. Yara plays it back twice, slowed down, and goes very quiet doing it.

"That's not a distress call anymore," she says. "That's a response."

"To what?"

She points at the frequency trace. The new segment starts exactly one second after your drive throttled down automatically at fifty kilometres — an internal event, nothing transmitted, nothing anyone outside this ship could have measured. And yet the new frequency sits precisely on the resonance of your own engines.

The captain says nothing for a while. Then: "It didn't hear us. It felt us."

Nobody argues, because nobody has a better explanation, and the consoles around you stay in their enforced silence.

The opening on the object's hull, twenty kilometres out, hasn't changed since the last reading. Not yet. But the return fuel keeps burning regardless of whether you make a decision, and the quiet on the bridge now belongs to three people, none of whom wants to be the first to ask the obvious question.

Then something moves at the edge of the optical feed, too small to name with any certainty, too definite to ignore.