Early in Ricki Stern and Anne Sundeberg’s extraordinary documentary portrait Joan Rivers: A Piece of Work, the legendary comic’s manager offers up an assessment of the general perception of his client. “Right now,” he says flatly, “they see her as a plastic surgery freak who’s past due.” Full disclosure: I was one of those people. My primary impressions of Rivers were of a, yes, plastic surgery freak, braying on a red carpet on E! (their exclamation point, not mine). I knew her as the woman who quit the gig guest-hosting Carson for a Fox competitor that flopped miserably; I knew her as one of the C-grade schlubs on “Celebrity” Apprentice (my quotes, not theirs). What I didn’t know her as was funny, or fascinating. In Stern and Sundberg’s excellent documentary, she is both.The film, subtitled “a year in the life of a legend,” begins with startlingly tight close-ups of Rivers’ (badly) sculpted face as she is made up. The proximity is shocking, but appropriate preparation for the picture to follow; they may be the only time we see her out of her make-up, but it is not the last time she lets her guard down. Rivers will turn 75 years old in the course of the film, but she isn’t slowing down. She is, in her manager’s words, “a chronic workaholic.” Early on, we see her and her assistant Jocelyn going over her “books”—the schedules of her various appearances and engagements. They’re looking too empty to Joan. She looks through an old book and sees busier days. “That’s a good page,” she says wistfully. “That’s happiness.” Stern and Sundeberg rotate between verité--style home and work footage, interviews, and Rivers’ biography. There are fantastic vintage clips of her on Jack Paar, Mike Douglas, and Carson, clippings, photos, memories. She’s surprisingly candid—she talks about her surgeries, talks about her marriage, her difficulties balancing work and family. “She referred to her career as ‘The Career,’” her daughter Melissa remembers. “And it occurred to me one day that I had a sibling.” And she remembers the rough years—the ugly break-up with Carson, the failure of the Fox show, the suicide of her husband Edgar (which, oddly enough, she and Melissa reenacted for a TV movie, a move she claims was rehabilitative but still seems mighty weird). The dynamic with Melissa is quite interesting—nobody sees through Joan quite like her daughter, and when they do Celebrity Apprentice together, we get a peek inside their relationship (Melissa seeking affirmation, or chastising her mother for turning her insecurities into criticism of their co-stars). Rivers’ involvement in that reality show might make one question the authenticity of her portrait here; is it an honest impression, or a calculated performance for the camera? I’m honestly inclined to think the latter—or at least, that it’s as honest a portrait as we’re going to get. Rivers has been performing so long, it could be said that she is always “on,” that the clear boundaries between person and persona evaporated decades ago. Whatever the case, the primary takeaway from Joan Rivers: A Piece of Work is how vulnerable she is. She pours her heart into an autobiographical monologue/biographical play called “Joan Rivers: A Work in Progress by a Life in Progress”; it kills at the Edinburgh festival, but when West End reviews are just so-so, she shuts it down instead of taking it to Broadway (her previously stated goal). Why? Because she was so badly hurt by the Broadway critics when she last appeared there—in 1972. “No one will ever take me seriously as an actress,” she says, and you can see the pain in her eyes. She fronts that she’s a tough broad, but the barbs hurt. As a protective measure, she’s her own worst critic; when she appears at the Kennedy Center tribute to George Carlin, she says of her fellow presenters, “they’re all gonna be so much funnier than I am.” But the toughest hits come when she subjects herself to the indignities of a Comedy Central roast because she’ll make some badly-needed money. “They keep telling you it’s an honor,” she muses. “If I had invested wisely, I wouldn’t be doing this.” Clips of the roast are seen, and the cracks are predictably vile; the filmmakers slow down the tape and hold on Rivers as she tries to keep her brave face on. Moments like that might stack the deck a tad too much in the icon’s favor, but who cares? Our goodwill toward Joan Rivers is strong enough even without those moments; she’s a survivor, she’s a hard worker, and most of all, she’s hilarious. Clips are interspersed throughout the film of her working new material in a small Manhattan cabaret, and she is explosively funny (and filthy as hell). She shows, in her office, a card catalog—30 years of jokes, alphabetized by subject, typed up on 3 x 5s. We see her out on the road, working the showroom of a Wisconsin casino (looking over her accommodations, she advises an assistant to get the check before the show), and she slays them—and when a heckler interrupts to protest the offensiveness of a joke, threatening to stop the show cold, she burns the guy right down to the ground. It’s an amazing piece of footage, but it’s reflex for her. This is what she does. “This is where I belong,” she confesses. “The only time I’m truly, truly happy is when I’m on a stage.” After seeing Joan Rivers: A Piece of Work, we’re inclined to agree."Joan Rivers: A Piece of Work" opens Friday, June 11th in limited release.