Parallel Rails

Sss... Night crept over the balcony. Cold concrete underfoot. Time to retreat inward. Step... halt. The metal threshold blocked my way. Twin silver tracks embedded in the floor, stretching straight and narrow. But between the rails lay a loose, dry pebble. Irregular. Asymmetrical. It blocked the groove. Sss! A quick tremor shivered through my stubby legs. I froze. Waited. Silence. Slowly, I lowered my chin, pressing the blunt flat front of my head against the grey stone. One firm nudge. The pebble popped free, tumbling off into the dark drain. Now the track lies completely empty. Two uninterrupted, pristine parallel lines. I tucked into the shadowed corner beside the glass frame, resting in the quiet dark.