The hum returned first.

A faint vibration threading through the reinforced bulkheads of the relay hub, like a living pulse buried in metal.

Gray froze mid-sentence, the readouts behind him flickering with sudden distortion. “Tell me you’re seeing this, Hale.”

Hale didn’t answer. He was already leaning over the main console, eyes locked on the fluctuating waveform spilling across the holo-display. The echo signature—a ghost they’d thought gone quiet—was back. Only now it moved ...