As a pilot with the Defiant Defense Force, Spensa's life has been anything but typical. She proved to be one of the best starfighters in the human outpost of Detritus, and she rescued her people from being wiped out by the mysterious alien Krell race that has been imprisoning them for decades. She also travelled light-years away from her home planet as a spy to infiltrate the Superiority, where she discovered the galaxy's vastness. A galaxy-wide conflict has now been sparked by the Superiority, the ruling galactic alliance determined to rule over all human life. And Spensa has seen the Delvers, the weapons they want to employ to put an end to it. Ancient, enigmatic alien powers that are capable of instantly destroying entire planetary systems.