Queen of Candesce — Karl Schroeder

Venera Fanning was last seen falling into nothingness at the end of Sun of Suns. Now, in Queen of Candesce, Venera finds herself plunging through the air among the artificial worlds of Virga, far from home and her husband, who may or may not be alive. Landing in the ancient nation of Spyre, Venera encounters new enemies and new friends (or at least convenient allies). She must quickly learn who she can trust, and who she can manipulate in order to survive.
Survival isn't her only goal; with the powerful Key of Candesce in her hands, she can control the fate of the entire world of Virga, yet something even more pressing is driving her--the all consuming need for revenge.