My book's a lousy book,"" says Riley, Irish author on a sojourn of enforced creation in America, "". . .you think you see a light ahead. . .only to fall once more into a swamphole of overladen prose."" On the whole, Riley is on target, except that the death struggles in the bogs have their own luminescent fascination. And Christy Brown, whose crippling paralytic handicap has become a fictional metaphor for the defensively isolated world of the sensitive writer, can also write with wit and efficiency: a man snoring ""like some oncoming overdistant train. . .beside him his little ferret of a wife knitting endlessly. . . ."" The imported Riley, as tempest-tossed as Eugene Gant, brings his trade (the ""clash of syllables"") to the never-never land of American publishing to he lionized and cosseted. And Riley's Esther Jack is Laurie, his hostess, who was ""fashioning him into a sensitive, industrious being. . .a primitive come down from the mountain."" Riley has a tortuous affair with a female photographer; he is chatted up and talked at; meanwhile he fights to know and yet be free of others, and free, too, of ""the insane urge to interpret and transpose life."" In spite of the half-page-long sentences and deadly dialogues with the straw-filled bores surrounding Riley, there is still some life in the Wolfean view of the writer as a destiny-driven colossus, to which Brown lends an intermittent, sad intensity. One awaits his return to the mountains. . .of Ireland?