The first invasion of Earth was beaten back by a coalition of corporate and international military forces. China has been devastated by the Formic's efforts prepare the ground for their own settlement. The Scouring of China struck fear into other nations; that fear blossomed into drastic action when scientists determined that the single ship that wreaked such damage was merely a scout ship. There is a mothership out beyond the Solar System's Kuiper Belt, and it's heading into the system, unstoppable by any weapons that Earth can muster. Readers will discover the past of Ender's world, feel the desperation of Earth that drove humans to make the changes they did and meet the heroes who fought off the tide of invasion until Ender could decisively end the wars.
When the alien ship screamed through the solar system, it disrupted communications between the far-flung human mining ships and supply stations and between them and Earth. So Earth and Luna were unaware that they had been invaded until the ship pulled into Earth orbit, and began landing terra-forming crews in China.
The mining ship El Cavador is far out from Earth, in the deeps of the Kuiper Belt, beyond Pluto, when its telescopes pick up a fast-moving object coming in-system. El Cadaver has a variety of other problems that worrying about an alien ship doesn’t seem important, but in fact, it’s the most important thing that has happened to the human race in a million years. The first Formic War is about to begin.