Featuring Rob Zombie, Dee Snider, and Lemmy Kilmister. Rated 14A. Opens Friday, February 24, at the Cinemark Tinseltown

This mockless documentary is well-crafted enough to make believers out of non-metalheads, and it's inside enough to get the devil's-horns salute from the most diehard followers.

Headbanger-turned-anthropologist Sam Dunn is a codirector here and our on-screen tour guide for the surprisingly variegated terrain that is post-'60s heavy metal. Clips from 1986's seminal short "Heavy Metal Parking Lot" set the stage for a level of cult devotion otherwise known only to country stars and professional wrestlers.

Interviews with the likes of Rob Zombie, Alice Cooper, Vince Neil, Ronnie James Dio, and Iron Maiden's articulate (and strikingly unweathered) Bruce Dickinson lay out some basic history. More bookish types like Donna Gaines and Chuck Klosterman suggest there's more intelligence behind those thudding chords than casual listeners might suspect-although Klosterman may have a bit of a reverse-snob thing on his agenda.

Of glam-metal veterans from the 1980s, Dee Snider comes across as the most insightful observer, especially when the former Twisted Sister frontman recalls facing down Tipper Gore in the infamous PMRC circus of the period. Motíƒ ¶rhead's mush-mouthed Lemmy Kilmister is also a highly entertaining presence.

Walking the line between obstreperous and scholarly, Dunn dissects the various schools that evolved after Ozzy Osbourne's Black Sabbath and others stole the "heavy-metal thunder" (a phrase coined in Steppenwolf's "Born to Be Wild") from Woodstock-era acts like Jimi Hendrix and Cream, emphasizing the dark and the loud, often at the expense of subtlety and subtext. After the plod rockers of the '70s came herds of hair bands, spandex-stretchers, speed-metal demons, power punkers and-creepy even to this crypt-kicking crowd-Norwegian black metal.

Dunn and company travel to Norway to examine some church burnings in the 1990s and the music's fixation on death and the devil. Other sections address sex, gender, and class. There's a quick reference to the primacy of African music in all rock 'n' roll, but Metal leaves its fascistic iconography and possibly racist impulses open to interpretation.

One might also wish that the filmmakers had included certain stalwarts such as Ozzy himself or members of Metallica. But the movie doesn't claim to be definitive and it does major justice to the fans, who are given time to describe how this axe-clanging music has enriched their lives and sometimes even saved them. The soundtrack, as might be expected, kicks some leather-clad ass.