This was the first book I've read by Karl Schroeder, and it was a pleasant discovery - I liked it well enough that I've already picked up a couple of other books by him. It's exciting sci-fi adventure with an unusual setting that reminded me a little of Flash Gordon (the movie). Virga is a bubble-like world, filled with floating cities and towns heated and lit by artificial suns. Settlements' wandering paths often take them into each other's way, causing political conflict. Hayden Griffin's life has been formed by such a conflict - his people, from the tiny nation of Aerie, perished in a rebellion against a larger nation, and he has been bent on revenge for years... but when he finally infiltrates the inner coterie of the powerful Fanning family, whom he believes to be his enemies, what he learns besets him with doubt. And when he meets a woman who says she is from outside Virga, and tells him strange things about the Universe outside Haydn's world, he realizes much more may be at stake than the future of Aerie.