The helix and the sword

6000 years hence, long after Earth has succumbed to pollution, the human race is dispersed throughout the solar system on huge living islands; "synes," whose production is monopolized by the mysterious, benevolent Sisterhood, have replaced machines and computers in the metal-poor economy of space; and two empires, the Imperium of Aresia near Mars and the Trojan Regency of Jupiter, both running short of usable matter, are at loggerheads over possession of the asteroid belt—with "The Hand of Man" (a reactionary, military theocracy) eager to seize control. So, to patch up the empires' quarrel, princess Linsang of the Regency is supposed to wed the Aresian ambassador—but she poisons the unappealing fellow instead. Then Linsang, sync expert Dyson Tessier, and Pantolog Five (an encyclopedia-syne in the shape of a cheetah) are captured and taken to a distant, eccentric cultural outpost—where they learn that war has broken out. And from there they must journey to abandoned, legendary Earth... to find a means to defeat the Hand of Man.