This first volume of a projected Keltiad hypothesizes a future encounter between a Terran space probe and a world-cluster that proves to have been colonized by the Irish about 3,000 years previously--under the inspired leadership of St. Brendan the Astrogator. (Having successfully salvaged one boatload of refugees from Christian persecution, St. Brendan went back over the next few centuries to rescue other ""Kelts"" from Scotland, Wales, etc.) In seeking a Terran alliance, the federated Keltia world-system (now ruled by the High Queen Aeron Aiobhell, a stunner with hair ""like copper lace"") precipitates war with the long-hostile world of Fomor and the treacherous Coranians--led by the yellow-eyed Prince of Alphor. And soon the Kelts' citadel of Caerdroia is breached by magic: Queen Aeron barely escpaes to seek help from the long-vanished hero Arthur. . . in the Morimaruse, the deadly ""electromagnetic void"" (Kennealy is none too exact on technicalities) where his ship is reputed still to sail. Throughout, in fact, the sf trappings here--force-fields, laser swords, hyper-space, sonic hair-dryers--are feeble. The borrowings from Celtic tradition are gimcrack. And, with the hollowest of sword-and-sorcery (""And the evil radiance began to stream outward from her hands"") adding to the mishmash, this is a fairly dismal saga sendoff altogether--showing neither the patient detail and discipline of Katherine Kurtz's Deryni books nor the imaginative force of Marion Zimmer Bradley's Darkover series.