I run packages through the Underworld. Not drugs — data, mostly. Physical media for people who don't trust wireless. I know the routes between B10 and B30 like I know my own apartment. On March 14, I was on a routine run through Sector 6, Level B22, carrying a sealed data stick from the Narrows to a client in Old Harbor. The B22 Sector 6 corridor is a straight shot, two klicks, well-traveled by couriers. I've run it hundreds of times.

Halfway through, I heard whispering. Not from behind me, not from ahead — from everywhere. The acoustic properties of the Underworld can play tricks, I know that. Sound bounces off concrete in ways that make distant conversations seem close. But this wasn't a distant conversation. This was close — centimeters from my ears, multiple voices overlapping, speaking too fast and too quietly to understand individual words but clearly producing structured speech. Like a crowd of people all whispering urgently at the same time, right beside my head, except there was no one there.

Then I saw them. Or saw something. In my headlamp beam, at the edge of visibility — maybe thirty meters ahead — the air was full of something. Particles. Like a swarm of insects, except they didn't move like insects. They moved like a fluid — swirling, contracting, expanding, forming shapes that almost looked like faces before dissolving and reforming into new shapes. The swarm was dense at the center and diffuse at the edges, maybe three meters across, hovering about a meter off the ground. And the whispering was coming from it.

I stopped. The swarm stopped. It contracted — pulled itself into a tighter formation, maybe a meter across, and the whispering got louder. Faster. More urgent. Individual words started to emerge from the noise. I couldn't understand most of them. But I heard my name. "Felix." Clear as a comm call. My name, in the middle of the whispering, spoken by something that I am confident was not a person, in a place where no person was.

I ran. I turned around and ran back the way I came and I didn't stop until I hit B15. I missed my delivery window. I refunded the client. I haven't run Sector 6 since. I've talked to other couriers. Three of them have heard the whispering. One of them claims the swarm spoke his mother's name — his mother who died four years ago. None of us run Sector 6 anymore.