“I’ll show you fear,” says Joan Rivers, opening her planner to a page with nothing on it. “If my book ever looked like this, it would mean that nobody wants me, that everything I ever tried to do in life didn’t work, that nobody cared and I’d been totally forgotten.”

The title of the documentary Joan Rivers: A Piece of Work has a double meaning. Love her or hate her, she always has been and remains, in the traditional sense, a real “piece of work,” a genuinely transgressive comedian who will make your jaw drop. If you’ve only ever seen her performing on network television, or on her red carpet gigs on cable, you have no idea, though you will after you see this.

But the title always reflects what matters most to her. Filmed in the year after she turned 75, it shows her obsessed to keep working, to keep her planner filled and to find ways to heat up her career when it isn’t.

Someone as blunt as Rivers is the perfect subject for a documentary. If there were any subjects the filmmakers shied away from, or which she refused to discuss, I can’t imagine what they could have been from the evidence of what’s here. Speaking about her husband and manager Edgar, who committed suicide after her 1980s talk show was cancelled, she says, “Was I madly in love with him? No. Was it a good marriage? Yes.”

Unlike Don Rickles, she can be authentically nasty, demonstrated in an exchange from a casino stage in Wisconsin from a man in the audience offended by a joke. You’ll think twice about ever heckling a comic again.

You may feel that she goes too far—she certainly tries to, opting at all times too offensive over too safe (though to her credit she discards a joke about Michelle Obama). You won’t necessarily feel sorry for her: Her work supports a pretty lavish lifestyle. But creature comforts are clearly not the entire reason she maintains the grind, and the glimpses into the psychology that has driven her into her fifth decade of a rough business make this a fascinating show business portrait.

—m. faust

Watch the trailer for Joan Rivers: A Piece of Work