Scott Westerfeld says that he set out to write the space opera that he would have liked, and he came up with one that a lot of us like. In this tale he weaves together an espionage story, political intrigue, romance, future history, the ethics and ramifications of artificial intelligence, the ethics and ramifications of immortality, a commando raid, and one of science fiction’s more elaborate and high-tech ship-to-ship battles. And this empire is ruled by heroes who have passed on to their reward, both literally and figuratively, as the emperor has the power to grant immortality to those who obey him, but only if they agree to die in the process. Originally written as one novel to be called Succession, the publisher decided to split the story into two books: The Risen Empire, and The Killing of Worlds. (They’re not sequels, but one story in two volumes.)