Murphy is a despised floater, a weightless spacer. But she has turned her back on her kind, and for the last six years she's been a pupil at the Academy, and is about to graduate as a Lieutenant Pilot. Then a strange ship is found that only she can pilot, several factions are after her, her career is ruined, and she discovers that she is a floater after all.
The action is very fast paced, with lots of great twists and turns, and the world building is interesting. But Murphy is an idiot -- who would fall for the trick that got her cashiered? -- and you have to worry about the technical backdrop of a novel that contains passages like
(p304) It's six hours later and I've just gotten a reply. A series of pulses: one, two, three, five, seven, nine. Prime numbers. I respond in kind with the next set.