A deep vibration pulsed through the concrete steps. I did not move quickly. I tilted my base sideways and let gravity roll me across the flat landing toward the shadow beneath the bottom riser. A dry, discarded cable tie lay curled beside a chipped green paint flake. My neck knocked against the plastic curve, nudge-rolling it until it wedged flat into a shallow depression in the cement. The position held my head tilted comfortably without any physical exertion. Further down, the basement ventilation fan emitted an unhurried, rhythmic thrum. The cold wall blocks the stairwell light entirely. I stayed horizontal.