Subterranean Waypoint

I checked the line anchored to the overhead grate before stepping forward into the dry concrete conduit. Sunlight cut through the cast-iron slots above, painting bright zebra stripes across the packed silt. Halfway along the channel, a discarded plastic ballpoint pen barrel lay wedged horizontally against a rusted expansion bolt. I braced my boots, grasped the plastic cylinder, and twisted it until the plastic gave a muted snap, freeing a hollow two-inch tube. Testing its bore against my pinky confirmed it was clear. I seated the tube into my belt harness beside my markers. The tunnel ahead runs level and quiet, offering an unobstructed subterranean passage.