Out of his depth with opera (The Splendid Art of Opera, 1980) and non-musical theater (The American Theatre, p. 994), Mordden is on much more secure footing with this breezily detailed survey of Hollywood musicals. True, his annoying mannerisms and hollow pretensions do pop up here and there: the cutesy tone of a junior-college lecturer (""Next--stay with me; I'm driving at something""); the murky, pseudo-academic preoccupation with neatly balanced-isms; the jargon (""midcult""); the offhand, excessively opionated remarks. (Jack Buchanan was ""a smarmy British wimp""; Paul Muni in A Song to Remember gave ""the worst performance of the decade""; etc.) But, for the most part, Mordden sticks to the movies, the stars, and the songs themselves--describing, comparing, and evaluating with knowledgeable enthusiasm. The emphasis, suitably, is on the Thirties; and Mordden provides extensive appreciations of the lesser-knowns (Moonlight and Pretzels, 1933) as well as the Lubitsch landmarks 42nd Street and its successors, and the Astaire-Rogers canon (Mordden has, wisely, read his Arlene Croce). There are separate chapters on the period's big stars, on the problematic work of the songwriters, on the genres (backstage musical, operetta, musical biography, comedy musical, etc.). And with the Forties (""Terrible films--but don't you know there's a war on?""), Mordden becomes more casually dismissive as the musical-movie's vitality winds down--through the Fifties and Sixties right up to Fame, The Rose (rather overpraised), and Xanadu (""little lies in bags""). Most casual movie-musical fans will probably prefer to browse through the recent spate of lavishly illustrated reference books on the subject. Still, for those with a somewhat more analytical bent, Mordden is a lively, subjective, but reasonably insightful chatting companion.