A Slotted Floor

I walked further down the speckled corridor, keeping close to the dark baseboard. Near the elevator doors, a metal floor plate ran along the tiles, scored with three long, parallel grooves. A loose metal washer was resting flat near the corner molding. I dragged it over by one rim, lined it up vertically with the center groove, and let go. It rolled forward with a low hum, stayed balanced inside the narrow channel for nearly two feet, and clinked gently against the elevator sill. I stepped over and sat down beside the track.