“I don’t know where people get this idea that it’s supposed to be fun or something to play music,” J Mascis says in his signature hyper-relaxed drawl, near the beginning of the new documentary Freakscene: The Story Of Dinosaur Jr. “That seems to hinder a lot of people: ‘Well it’s not fun, why should I do it?’ That never occurred to us that it’s supposed to be fun. It’s just, music was really important and we wanted to do it.”

If you’ve read even a little about the history of this band, the quote rings true. Despite Mascis’ ultra-chill personal affect, so borderline-comatose that it’s hard to believe he’s been straight-edge for four decades, Dinosaur’s internal dynamics were famously tortured during their initial run. That, plus the band’s formidable legacy within alternative rock, make them obvious candidates for an indie-scale documentary. Now they’ve got one in Freakscene, directed by Philipp Reichenheim, the German filmmaker also known as Philipp Virus. Reichenheim, who also directed the 2007 concert film Dinosaur Jr.: Live In The Middle East, is Mascis’ brother-in-law, and Mascis is credited as a producer on Freakscene. But the movie doesn’t pull punches where Dinosaur’s dysfunction is concerned, even as it makes the case for their place in the indie-rock pantheon.

Those seeking as much painstaking detail as possible about the band’s history, infighting included, should check out the Dinosaur Jr. chapter in Michael Azerrad’s canonical ’80s underground rock history Our Band Could Be Your Life. Freakscene paints in broader strokes, but it certainly gets the point across. To do so, it pulls from extensive chats with Dinosaur’s three founding members and ropes in an all-star team of interviewees including Black Flag’s Henry Rollins, Sonic Youth’s Kim Gordon and Thurston Moore, My Bloody Valentine’s Kevin Shields, Hüsker Dü’s Bob Mould, the Pixies’ Frank Black, the journalist and zine pioneer Byron Coley, Sub Pop’s Megan Jasper, her sister Maura Jasper (the artist responsible for Dinosaur’s iconic cover art in the ’80s), and more. Several of these folks are documentary talking heads on a regular basis, but it’s fun to see how many big names turned out to pay homage to this band, even if some noteworthy players do not appear. I would have liked to hear from the band’s 1980s label heads Greg Ginn (of SST) and Gerard Cosloy (then of Homestead) — particularly Cosloy, whose history with Mascis and Lou Barlow dates back to before the formation of Dinosaur. On the other hand, the most trenchant insights in the doc come from the band members themselves.

The first half of Freakscene is more narratively driven, telling the story of how Dinosaur Jr. started to implode even before their popularity exploded. After a brief segment dedicated to Deep Wound, the overachieving Western Massachusetts hardcore band for which a teenage Barlow thrashed the guitar and Mascis bashed the drums, the Dinosaur story begins. In keeping with a nationwide movement away from straightforward hardcore toward artier, more melodic sounds, Mascis switches to guitar, starts writing songs, and founds a new band that pulls as much from classic rock as punk. He recruits the introverted Barlow to play bass, “which always surprised me because I thought he hated me,” Barlow recalls. Mascis rounds out the lineup with a hippie-punk drummer by the name of Murph, born Emmett Jefferson Murphy III, whose carefree vibe and fondness for drugs run counter to his bandmates’ stoic hardcore backgrounds. Several delightful minutes are devoted to Mascis and Murph describing each other’s demeanors and personal styles; the photos from those early days are spectacular.

In spite of (or maybe because of) all their baked-in personal friction, the band quickly hits upon an inspired signature sound: a sludgy, deafeningly loud strain of punk-based guitar-pop topped off with electrifying Mascis guitar solos. In an attempt to capture the same visceral feeling he got from playing drums, Mascis runs his guitar through countless effects pedals and cranks it up to unimaginable volumes that sometimes send Barlow and Murph running to the bathroom to hide during rehearsals and get Dinosaur banned from more than a few venues across America. But Barlow is impressed by Mascis’ songwriting and devoted to “the absolute purity of his vision,” and Murph is similarly enthused about the chemistry they’re developing. Soon, so are tastemakers like Sonic Youth, who take them out on tour in 1986 between Dinosaur’s first and second albums: “our only fun tour,” per Mascis. Brief though it may be, footage of the two bands chilling outside a house in Buffalo is one of the film’s most pleasing archival treasures.

But when Dinosaur head out on the road the following summer ahead of their breakout sophomore album You’re Living All Over Me, it’s far from a blast. A series of van breakdowns leads to a week stranded in Mountain Home, Idaho, where Mascis makes sport of belittling Barlow and Murph takes out his frustration with his bandmates by destroying a mattress. (It’s Murph who offers up the movie’s best quote beyond that Mascis line about not having fun: “I guess I always felt like I was waiting for those guys to grow up. I couldn’t figure out why they were so immature. I was like, ‘What’s with you guys? We’re a good band. Why don’t you get with it? Why don’t you step up to the plate and make this shit happen?’ Because to me it was easy. The social part was easy. Integrating, being with people was easy. And I didn’t understand that for them, that was hard.”)

From there Freakscene chronicles Dinosaur’s rise to underground celebrity, low-grade MTV stardom, and the inevitable major-label horror story, making sure to point out how acts like Nirvana looked up to them (and once opened for them). In parallel, the film traces the gradual disintegration of Dinosaur’s original lineup — first Barlow’s departure after 1989’s Bug, then Murph’s at the peak of Dinosaur’s mainstream exposure — and Mascis’ eventual decision to end the band. There are Y2K-era wilderness years, the original lineup’s triumphant mid-aughts reunion, and, climactically, a star-studded 30th anniversary concert series at New York’s Bowery Ballroom in 2015. Along the way, Mascis gets deep into Eastern spirituality. Murph gets sober. Barlow’s various other bands (Sebadoh, Folk Imposion, etc.) get little to no mention, but he happily reports that Dinosaur were able to reconcile because they’d grown up and gotten over themselves.

Once the movie hits the reunion phase, the emphasis shifts to Dinosaur’s legacy. Mould claims Mascis opened up a lane for musicians to experiment with guitar noise in more of a pop context, essentially crediting him as a forefather of both grunge and shoegaze. Frank Black provides a hilariously physical, onomatopoeia-filled description of the Dinosaur sound. Murph says he can finally appreciate the band’s history, while Barlow suggests Dinosaur deserve to be held up alongside titans like the Ramones and the Velvet Underground. A lot of context is left unspoken, and a lot of details are skipped over, but given Mascis’ knack for brevity and understatement, that’s not too surprising. If you want to get deep into the weeds, you should definitely read Azerrad’s book. The draw here is the old footage: Kennedy interviewing Mascis on MTV, Dinosaur wrecking nightclubs in the ’80s, David Letterman introducing “Feel The Pain” on The Late Show, the reunited Dinosaur posing for a photo with Rollins and Ian MacKaye backstage at a show. The movie is an appropriate document of a band that has always been more about overwhelming sensation than precise communication.

Freakscene will be in theaters across America for one night only on 5/31, followed by a couple stray screenings on 6/3 and 6/4. Before that, Mascis will perform and answer questions at Freakscene showings at the Opera House in Brooklyn this Saturday, 5/28, and the Amherst Cinema in his hometown of Amherst, Mass. on Sunday, 5/29. Get details on everything here.