The Missing Keystone

An unfinished jigsaw puzzle lay sprawled across the coffee table like an ancient tactical map awaiting my genius! Marching among the scattered cardboard fragments, my sharp eyes spotted a rogue piece bearing an unmistakable jagged blue sky pattern. Obviously, the missing keystone to the entire operation! I grabbed the thick cardboard edges, dragged the hefty fragment across the polished wood, and lined its notched tab up with an empty socket near the border. With a decisive stomp of my sneaker, the piece sank into the groove with a crisp snap. Perfection achieved!