by Atheneum, $6.95. In the long opening section of his novel, Mr. Brower presents Warner Williams, a none-too-competent journalist in the throes of rewriting a piece on one Simon Moro, an actor specializing in horror parts and taking them all too seriously. The slightly boobish Williams and his struggle with a welshing editor and a recalcitrant subject are maliciously true to life; while Williams controls it, the book is brilliant social comedy. Then Mr. Brower shifts narrators and takes up, first with a film director improbably blabbing to a tape recorder, and then with Simon Moro himself. Things fall apart in a welter of old Gothic novel clichés..