The crucial question in Penelope Spheeris's trilogy of The Decline of Western Civilization documentaries comes in the first shot of the little-seen Part III. In a black-and-white talking-head interview, Spheeris asks Why-Me, a 16-year-old gutter punk who hadn't been born when the first documentary in the series was shot, "How is punk rock different now than it was in 1979–80?"

"I don't think it is," he replies. "I mean, it's the same. I think it's smaller?"

Here the camera zooms out to reveal the full extent of Why-Me's costume: improvised Mohawk, bridge piercing, and jean jacket bedazzled with studs, pins, and hand-stenciled logos for bands like Subhumans, Disorder, and MDC. In other words, punk rock central casting's standard-issue look for the past 40 years, and evidence that what he says appears to be true—the fact that the year is 1997 is just a coincidence of filmmaking.

"But people care about it more." He then smiles a warm, sweet, guileless smile that belies every single nihilistic thing about his appearance. His humanity is irrepressible, despite all the attempts he and his circumstances have made to repress it.

It's easy to read such a moment cynically, particularly if you have a lot invested in your personal relationship with punk as a political or aesthetic movement. That cynicism is easily borne out by the music performances throughout the rest of the film as well, by 34th-generation LA punk bands with names like Final Conflict, Litmus Green, the Resistance, and Naked Aggression (who chime in with a number called "Smash the State"). The rehearsal of familiar punk looks and sounds has been bumming older punks out since the Bromley contingent first arrived in London. But that objection hasn't done anything to diminish the allure of the gesture for younger generations of either musicians or fans—much to the further consternation of the dusty oldsters resisting the process of outgrowing it. (Silver Jews' David Berman expressed this perfectly in the line "Punk rock died when the first kid said, 'Punk's not dead.'")

And yet, like its two predecessors, The Decline of Western Civilization, Part III is a riveting document of the long, slow, stubborn death of rock 'n' roll. For all the attraction of bands like Black Flag, Germs, and X playing live at the height of their initial energy, and all the ketchup of punks and heshers living up to their dopey, drunken archetypes, these films are far more complex, more curious, more moral, more conscientious, and more suffused with love than their surfaces might indicate. And like the weirdly durable phenomenon of punk itself, they take entirely unforeseeable turns on their route to immortality.

The director was hip-deep in raw footage of LA's first wave of punk culture before she understood that the films could be more than just a snapshot of a showbiz moment—which, because it was LA, was exactly how it presented. Over 20 years and three films, however, her tenacity and craft had generated a thorough sociology of a subculture's self-definition.

"Ultimately," Spheeris tells me on the phone from her LA production office, "the whole effort for me was about studying human behavior and trying to understand why young people act the way they do. The music is kind of a background for that."

If the first film is a desperate attempt to capture an exploding powder keg before it fizzles (which it assuredly did, thanks to some of the people in the film dying out and others cashing in), the second one is a bemused look at the fallout of that explosion. The Metal Years has become one of those movies that everyone in rock culture can quote, chapter and verse—and rightfully so. The scenes of Paul Stanley lying on a bed of hungry groupies, of ancient sleaze Bill Gazzarri trying to stir an indifferent crowd to get excited about a lousy band called Odin at his rock 'n' roll toilet of a Sunset Strip club, of all the bands being ragingly not even remotely good are shocking to behold.

Whereas the punks of 1979 and 1997 could plausibly come marching down Broadway right now and none of us would bat an eyelash, if anyone who looked remotely like a member of Odin or Vixen (or London, or Poison) brushed against you on a bus, you'd get a repetitive stress injury from taking surreptitious pictures of them on your phone. This footage retroactively puts the lie to This Is Spinal Tap (which Spheeris says she was offered the job of directing) and forecasts the headbanger burlesque of Wayne's World (which she did direct), though neither film comes close to suggesting the intensity of the dark side of that life. The scenes of W.A.S.P.'s Chris Holmes, drunk-to-obliteration, guzzling vodka and spewing suicidal self-contempt while floating in his mother's swimming pool—WHILE HIS MOTHER LOOKS ON SILENTLY SHAKING HER HEAD—are unprecedented in metal culture, and complicate any reading of the Decline films that doesn't focus on their humanity. And how that humanity was warped by the changing times.

"It was sort of shocking in Decline II," Spheeris recalls. "The bands all had this common consciousness of 'Let's make it!'"

What does she think inspired such a change from the days of the first film, where Black Flag squat (dis)contentedly in their dingy church rehearsal space/house and Darby Crash bounces around like a scarred-up pinball? How did it come to a state where Ozzy Osbourne, Dave Mustaine, and Steven Tyler were the voices of wisdom?

"I think it was just an observation that young people made," Spheeris says, "that having those attitudes that went on previous to them didn't work. You know? The hippie movement didn't work. Peace and love didn't work. (I had too crappy an upbringing to be a peace and love kind of person but I thought it might work.) And then punk rock comes in and... it think it kind of worked, but because it doesn't innately want to publicize itself, it doesn't spread fast. Then those metal kids come in and they're like, 'Screw those do-it-yourself-basic-I-don't-need-nothin' punk rockers. We want everything!' It's just a reaction. Every rock 'n' roll movement tries to destroy the one before it. It's really about each generation trying to make an identity for themselves."

So, despite the films' reputation, they weren't trying to make fun of these bands?

"Not at all," says Spheeris. "It wasn't ridiculous when we were doing it."

Spheeris's daughter, Anna Fox, who oversaw the release of the Decline box set and who was an LA teenager during the Metal Years period, underlines the point that the desire for showbiz success was "just a more common idea by that time. Even with the groupies. It was okay to be a groupie and be treated the way they were treated. That was actually a goal. That was just the consciousness of the times."

And it's not as though the consciousness of the times between now and then has been so exemplary, either. The most palpable element of Part III, which is the real revelation in this box, is the way the music is really just a component of the larger context of these homeless kids' lives. The world is harder and less forgiving than it was when the original punks first embraced the cast-off identity. In the meantime, the middle-class buffer between the wealthy and the forgotten has disintegrated. This reveals the essentially middle-class nature of concerns like cynicism about punk purity, embarrassment over the unoriginality of titles like "Smash the State," and, more generally, concern about the "relevance" of punk rock as a lifestyle choice. These are luxury items unavailable to and unimagined by the films' subjects. Whether or not Why-Me strikes a 40-year-old with a slowly smearing Black Flag tattoo under their oxford shirt as "authentic" could not matter less. To anyone. Punk isn't so much a choice for him and his gutter cohort as it is the one form of expression available to allow them to feel that their lives involve even a particle of choice. The fact that its aesthetic is so clearly pinned to choices that were made by bands, managers, and designers years before they were even born—back when the dustbin at least had flowers in it—makes the condition all the more poignant.

A few minutes after the opening scene, Spheeris asks him what he thinks is most fucked up about the world, and he replies, "Everything... sucks."

After seeing these utterly essential films, who's going to argue?