Posthumous collaborations between a biographer and his subject are rarely successful (consider last year's Conversations with Katherine Anne Porter by Enrique Hank Lopez), and this vast report on the life of James M. Cain, derived in part from his unpublished memoirs, is no exception to the rule: Hoopes faithfully includes details and anecdotes galore--without ever capturing either the flavor of a personality, the shape of a life, or the import of a career. (Following Cain's wishes, he did ""not write a 'critical biography.' "") True, Hoopes starts out with a couple of intriguing questions: ""Why did a man who had accomplished so much feel he had done so little--and why, in his writing, did he have to pretend to be someone else?"" Yet neither question is really explored--as Cain is painstakingly followed from precocious childhood as a headmaster's son to underage college graduation and brief music-career dreams; from WW I service to years of journalism--articles for Mencken's Mercury, editorials for Walter Lippmann, a brief New Yorker stint, ""rollicking nights out with the boys"" of the 1920s newspaper/magazine fraternity. His first literary successes were backwoodsy dialogues for the Mercury. (""Why Cain could not write about people in his own walk of life is a paradox yet to be resolved."") He struggled with a first novel, went to Hollywood to try making screenplay money, finally finished The Postman Always Rings Twice--a huge triumph, but though followed by a few other successes, merely the prelude to decades of restlessness: money problems; the never-ending battle to get the screenplay knack (a failure, despite the hit filming of Cain novels); four childless marriages; his sometime campaign for authors' rights (the American Authors' Authority); his vain attempt to gain greater prestige--with serious historical novels. In Hoopes' telling, the life, in fact, seems long but unusually uneventful--and since there's no attempt to look behind any of the surface facts (or too deeply into any of the fiction), this is an unusually dull biography. (Hoopes' YA-ish prose doesn't help: ""H. L. Mencken was one of the most unusual characters in American literature. . . . The war shook Cain to the core-personally and professionally."") Still, for sheer information-gathering, Hoopes deserves credit-and for allowing in some of Cain's unpleasantries. (On the Nisei Japanese: ""they had themselves to thank . . . if they weren't a nation of spies, they were giving a helluva imitation of it."") And perhaps some more probing biographer will find a dramatic life/work study within this unselective assemblage of facts, quotes, summaries, anecdotes, trivia, and bland assessments.