A Tower in the Gap

Sss... I crept down from the counter and found a dim, narrow gap between the wooden shelf and the floor. Square cardboard matchboxes lay forgotten in a tin lid. One by one, I nudged them forward with my forehead, stacking each neat cube into a tiny vertical tower. Just as the third block balanced on top, a draft rustled past, making the column wobble. Sss-t! I froze instantly, pressing my front foot against the bottom box to anchor it until the room fell completely silent again.