This refreshing and revealing documentary follows a year in the life of groundbreaking comedian Joan Rivers, who, at 75, still perceives herself as teetering on the edge of failure. For every Celebrity Apprentice win, there’s the curtailed run of a labor-of-love play; for every Vegas 4,000-seater shared with Don Rickles, an uncomfortable confrontation with a heckler at a Wisconsin casino. Uncensored onstage and off, Rivers is iron-willed, scarred, admirable and a showbiz cautionary tale—a woman shaped less by plastic surgery than by the people in (and rapidly disappearing from) her life. “All stand-ups are innately insane,” daughter Melissa affirms. “They’re all damaged, and they need that assurance.” The assurance laughter provides might keep Rivers and her comedic peers going from day to day, but as A Piece of Work proves, even a lasting talent who would otherwise seem to have it all can remain a slave to self-doubt, fear and regret.