The war raged across the galaxy. Billions had died, billions more were doomed. Moons, planets, the very stars themselves, faced destruction, cold-blooded, brutal, and worse, random. The Idirans fought for their Faith; the Culture for its moral right to exist. Principles were at stake. There could be no surrender. Within the cosmic conflict, an individual crusade. Deep within a fabled labyrinth on a barren world, a Planet of the Dead proscribed to mortals, lay a fugitive Mind. Both the Culture and the Idirans sought it.
After a harrowing battle flashback, the scene shifts to one of the Culture's wonderfully landscaped, ring-shaped artificial worlds called Orbitals. A ghastly light is awaited in the sky from distant suns detonated in the war of Consider Phlebas eight centuries earlier; an occasion for sombre festivity, pyrotechnics, and a memorial symphony from exiled alien composer Ziller.
The novel revolves around the Idiran-Culture War, and Banks plays on that theme by presenting various microcosms of that conflict. Perhaps surprisingly, especially since this is the first (published) Culture novel, its protagonist Bora Horza Gobuchul is actually an enemy of the Culture.