Louisville, Kentucky, band Slint have long been an enigma. Lance Bangs’s documentary Breadcrumb Trail devotes its 93 minutes to demystifying these often emulated but never equaled post-rock greats while also offering a brisk history of their city’s fecund punk-rock scene and its inhabitants’ “insane” (Slint fan Ian MacKaye’s word) nature. Breadcrumb is a revelation for obsessive Slint aficionados, tracing the band’s origins to a 1980 experimental public school that treated students like adults. Bangs moves chronologically through Slint members’ early musical machinations as absurdly precocious prepubescents; turns out they were gifted with ears for the unusual right from the jump. In the ’80s, they scored gigs with much older punks before they were strong enough to haul their own amps. Quotes from friends, former band members like David Grubbs, luminaries like James Murphy and David Yow, engineers Steve Albini (who produced Slint’s killer noise-jazz debut LP, Tweez) and Brian Paulson (Spiderland), and drummer Britt Walford’s parents color Breadcrumb Trail with quirky anecdotes and reveal Slint’s chronic pranksterism.

On record, by contrast, Slint seem like sensitive, smart guys who would nevertheless slash your jugular if provoked. They kept their passion on a tight leash, so when it was loosed, the outbursts hit with devastating impact. The phenomenal chemistry among Walford, David Pajo, Brian McMahan, and Todd Brashear culminated in 1991’s consensus masterpiece, Spiderland (cut in one weekend), but the band split before Touch and Go released it and the album slid into cultish obscurity. But via word-of-mouth evangelism from key tastemakers, Spiderland gradually accrued legendary status. The opus blueprinted unprecedented scenarios of loud/quiet and hard/soft dynamics and oozed a stoic majesty that stirred profound emotions. Fans have thought Slint were deadly serious, but Breadcrumb reveals that they recorded scatological cassettes titled Anal Breath and harbored large reptile collections. In the film’s last shot, Walford seems bummed that nothing in his life’s subsequently yielded the magic he had in the short-lived Slint. He’s not alone in that thought.