Spearpoint, the last human city, is an atmosphere-piercing spire of vast size. Clinging to its skin are the zones, a series of semi-autonomous city-states, each of which enjoys a different - and rigidly enforced - level of technology. Horsetown in pre-industrial; in Neon Heights they have television and electric trains ... Following an infiltration mission that went tragically wrong, Quillon has been living incognito, working as a pathologist in the district morgue. But when a near-dead angel drops onto his dissecting table, Quillon's world is wrenched apart one more time, for the angel is a winged posthuman from Spearpoint's Celestial Levels - and with the dying body comes bad news.