A tale of military adventure in a universe of star spanning colonies.
It starts with a pilot chasing a frightened young man in a yacht, and a near collision with a freighter, and after an ice giant. Untangling this brushes on the history of Earth and other planets, the fights known as the Establishment Crisis, and a con man. What unfolds out of this is that a poor planet is under attack -- it's not clear from whom -- and the poly (read: corporation) that nominally controls the system thinks it's not worth the expense. The pilot organizes some support, two old squadmates, the con man, and a pilot from the other side of the fight, to try.
Things thicken from there. It includes questions of how much to reveal to people, a strip mine that is new, a rousing speech, the possibility of building guns, post-traumatic stress and improvising, startling revelations, and much more.