With its mythic mists and galloping legends, fifth century Britain is fair game and Miss Stewart takes to whole cloth with a couturier's skill. This time applied to Merlin--a seer, Arthur's evil genius and resident engineer--all depending on whether you have your faultless facts from Geoffrey of Monmouth, Malory, Tennyson or a ouija board. Miss Stewart artlessly confesses in an afterword that she followed Geoffrey but loosely and gaily admits anachronisms. (There are Pendragonian sallies: ""you were perhaps a little--drastic?""; or bland references to the then non-existent ""Germany"" or ""Ireland."") In any case this is all Merlin's tune--from childhood as a despised bastard at the court of his grandfather the King, with his mother, the King's daughter, who wasn't telling who downed her in the dell. Then after secret tutorials in the cave of an old clairvoyant and scholar, Galapos, an escape to Count Ambrosius, a ruler who turns out to be. . . . Many ceremonials, prophesies and wars later, Merlin accomplishes his greatest coup--a procurement exercise resulting in the conception of Arthur by Uther Pendragon out of the Lady Ygraine. Period play, ripe and windy, for ladies easily lulled--and there are many of them.