After Westerfeld's excellent first installment, The Risen Empire (2003), in which a far-future empire of 80 worlds depends on its ruler's ability to give his most loyal subjects immortality, this concluding sequel comes as something of a letdown. That said, the author does a superb job of depicting an escalating space battle between human and rival Rix (cyborg) forces, with its constantly amazing but logical weapons and tactics, as well as political maneuvering back at the imperial capital. Vivid characterization and a witty, laconic style lift this far above the space-opera average. Readers, though, will need to go back to the first book to understand what makes the struggle between the empire and the Rix significant to meet Laurent Zai, brilliant space captain, whose allegiance to the emperor is weakening, and his lover, Senator Nara Oxham, who believes that the promise of immortality is choking human evolution. Without this personal perspective, the displays of military hardware come across as merely clever. At the end, huge promising and threatening changes have just begun. Despite the billing as the second half of the story, some may suspect that there's at least a third half lurking offstage.