This is a novel about The Theatre. It is also about the people who either ""make it"" or don't therein. On the first count, The Devil's Profession is a prodigious success. Where Mr. O'Neil attends to the institution and its trappings -- Sardi's after an opening, Whelan's before an audition, pre-Broadway guessing games, second act repairing, officious receptionists, sleeping around (home, hetero-, and bi-), the vicissitudes of career marriages -- he does just fine. But the fabulous invalid in this case is characterization. His leading lady who has everything but children is drawn with the subtlety of a Photoplay cover story. And she, together with talented ingenue, aging Jewish producer, fag agent, malevolently ambitious young buck, pregnant ingenue, et al don't come off any better than a second-rate stock company. For the Saturday afternoon matinee crowd.