For nine hundred years, a dynasty of Empresses all named Shira--apparent descendants of a refugee from a nightmarish future epoch--has governed Earth and all the new worlds of humankind. But now rebellion looms at last. In Alpha Centauri System, a visionary named Flood has assembled a fleet, armed with ferocious weapons, its mission to attack the Empire and force its surrender. Flood is prepared to bombard Earth into submission if need be, smashing its cities, killing billions... Why? What is at the root of his singular fanaticism? Without answers to this riddle, the combatants prepare for war: rival fleets of starships; stealthy invaders concealed within a comet; intelligent information-eating viruses with infinite appetites; contemplative ascetics living just above the surface of the Sun. And others...