Earth has been taken over by the mysterious entities known as the Builders, which have made humans' latest military technology usable only to them and have used modern aircraft, tanks, and ships to destroy cities and settlements and erect massive Pillars in their place. Humanity's only hope is a ragged collection of squadrons flying outdated warplanes in seemingly impossible fights against their modern replacements—in particular, the formidable group of young women called the Third Aerial Girls Squad.