A century from now, thanks to a technology allowing instantaneous travel across light-years, humanity has solved its energy shortages, cleaned up the environment, and created far-flung colony worlds. The keys to this empire belong to the powerful North family - composed of successive generations of clones. Yet these clones are not identical. For one thing, genetic errors have crept in with each generation. For another, the original three clone "brothers" have gone their separate ways, and the branches of the family are now friendly rivals more than allies.