One should not, the old saw says, judge a book by its cover. Is the principle the same if you judge a movement by its spelling, or a band by its look? I admit, with slight self-consciousness, that when I said goodbye to Buffalo, N.Y., and hauled my blue-collar life to D.C. in the mid-1990s, I was still discovering Bruce Springsteen (!) and enthusiastically warbling along to my first piano man, Billy Joel (!!). Musical try-too-hards with retro rags and hipster haircuts made me roll my eyes. It all seemed like a put-on to be cooler than thou. Yet I never listened to a second of their songs.

The Punk Singer, Sini Anderson’s debut documentary about Bikini Kill singer and riot grrrl pioneer Kathleen Hanna, therefore, sounded like an education at best and an 80-minute bore at worst. Never did a third option cross my mind: It’s fucking awesome, and energizing, and inspiring. Is there a cutoff age for starting a band?

Anderson starts the film with a home video of Hanna in 1991 Olympia, Wash., performing a spoken-word piece at a party. Her repetitions and rhythms will get in your head, but the work is more notable for other details, such as the lines, “There’s not a guy big enough to handle this mouth” and “I’m your worst nightmare come to life because I’m going to tell everyone! I’m going to tell everyone!” (Quite prescient, that.) Hanna wanted to become a writer. But Kathy Acker, a counterculture writer Hanna admired, told her that no one listens to spoken word, and instead she should be in a band.

So along with Kathi Wilcox, Tobi Vail, and Billy Karren—with Hanna at the front—Bikini Kill was born and came out screaming. The band played loud, fast, and primitively; the members weren’t exactly masters of their instruments. And Hanna demanded its performances be grrrl-friendly, making room in the mosh pit for fans who were likely to suffer broken bones and elbows to the face at other guy-heavy punk shows.

The Punk Singer’s footage of live performances are electric, but Hanna’s messages—and the messages of the movement—are the doc’s crux. She spoke out against sexual assault, discrimination against the voiceless, society’s dismissal of women’s perspectives, and tsk-tsking of female aggressiveness. Feminism is a concept that goes back decades—centuries, even—but as Hanna says, there’s still a need to fight.

The documentary covers Hanna’s follow-up bands (Le Tigre, The Julie Ruin), but also dedicates the film’s last chapter to Hanna’s mysteriously failing health, which eventually kept her from performing. (Although, pride still intact, she told people it was her decision to quit.) Her bizarre array of ailments were initially misdiagnosed; in 2010, Hanna finally found out that she’d been living with Lyme disease for five years.

Hanna may be a little worse for wear now, but proper treatment has helped her return to performing. And, of course, to speaking out. “‘I would never want to tell everyone [my] whole entire story because it sounded crazy,” she says, alluding to issues with her father that included “sexual inappropriateness,” in her words, and her seemingly hypocritical stint as a stripper. “It sounded like too big a can of worms, like, who would believe me? And then I was like, other women would believe.”