For forty years, a single sustained tone has occupied 147.3 MHz on the GLMZ industrial band. It does not waver. It does not degrade. It broadcasts from somewhere in the corridor between GLMZ and the Gary ruins, but no triangulation effort has placed it closer than a twelve-kilometer radius. The signal is registered to no corponation, no municipal authority, no private license holder. It simply is.

Twice per decade, on no discernible schedule, the tone ceases. In the silence — never longer than thirty seconds — a voice speaks. It gives a name and a number. The names belong to no one in any accessible database. The numbers correspond to nothing: not frequencies, not coordinates, not dates, not account identifiers. Then the tone resumes, as if it had never stopped.

The signal has survived three major infrastructure collapses, two EMP events during the Corporate Wars, and the complete destruction of the Gary industrial grid in 2171. It should not exist. Every piece of broadcasting hardware that could generate a signal of this consistency and duration in the affected corridor has been catalogued and accounted for. None of them are responsible.

We have received seventeen formal requests to investigate the signal's origin over the past decade. Each investigation has concluded with the same finding: the signal is real, it originates from a location, and that location contains nothing. The most recent survey team reported that the signal was loudest at the center of an empty concrete foundation — no structure, no equipment, no subterranean installation. Just a tone that has been broadcasting longer than most of the team has been alive.