The Peregrine

"They called themselves the Nomads. Unplanned by-products of the chaotic explosion of humankind into space, they had evolved for themselves a way of life similar to that of the gypsies of ancient Earth-except that their gypsy wagons were mighty starships, each a self-contained world that housed a clan of many thousands. It was a hard life, but the only one the nomads knew, or wanted. But someone, or something, did not want them to have it; one by one the nomad starships were disappearing without a trace-and it fell to oachim, Captain of the Starship peregrine, to find out why..."Everybody knows' that Poul Anderson is one of the best: they're wrong-he's better!"