Semi-apolytical young adult sci-fi series. In the future humanity has been drive to near extintion. The few remaining survivors are constantly fighting invasions on the planet of Detritus. Spensa grows up to pilot one of their few remaining starfighters against the invading Krell. If the Krell manage to get a bomb to their base, they lose their only ability to manufacturer more starfighters and are at the mercy of the Krell. The first book follows Spensa's fight to stop the Krell from attacking their planet. The second book follows Spensa being a spy on Superiority's base to figure out how to stop them. The third book follows Spensa traveling the Nowhere trying to figure out what the Delvers are and why they keep trying to kill everyone in the galaxy.
The first two books were some of the best I've ever read. The third book dragged a lot and was kind of hard to get through. Still waiting for the fourth book, but hoping it is more like the first then the third.