This is the third novel, after Sun of Suns and Queen of Candesce, to be set in Virga, a bubble universe artificially separated from our own future universe.
Chaison Fanning, the admiral of a fleet of warships introduced in the first book, had been captured and imprisoned by his enemies, but is now rescued and set free. He must flee to his home city to confront the ruler who betrayed him. Perhaps while there he will also regain his lovely, powerful, and subversive wife, Venera. He has not seen her since she fled, careening off into the air of Virga, with the key to the artificial sun, Candesce, at the center of Virga. In Pirate Sun, Schroeder sets a whole new standard for hard SF space opera.