"I just wanted some red meat," said Joe Berlinger, who came to Texas on a vegan diet. And though a steak at the Austin eatery Sullivan's may have done the trick for his taste buds, Berlinger and his partner Bruce Sinofsky needed something bloody good for their next feature documentary.

The resulting film, "Metallica: Some Kind of Monster," is a masterpiece of the rock doc genre, though as Berlinger notes, "The only concert footage you see is at the end of the movie."

Instead, the film chronicles the tumultuous off-and-on making of "St. Anger," an album started without bassist Jason Newsted, who quit the band in 2001, and marked midway by the temporary departure of lead singer James Hetfield, who entered treatment for alcoholism. While this would have already been compelling enough for two separate films, Berlinger and Sinofsky's ability to eavesdrop into the metal band's therapy sessions made for one unbelievable moment after another, even to the filmmakers.

"It's about a band approaching a midlife crisis," said Sinofsky. "And the strangest thing is in that very first session, Lars [Ulrich, Metallica's drummer] said, 'We've been together for 20 years, and I don't think I know you guys.' We were sort of dumbfounded, and maybe he was just making a very broad statement, but as it turns out, these guys really didn't know each other as they matured, as they became parents, as they became husbands."

To a lesser degree, the situation Sinofsky describes could've just as easily been about his relationship with Berlinger. In an area of film not known for celebrities, the duo are considered rock stars. After redefining the documentary form with exceptionally invasive murder mysteries like "Brother's Keeper" and "Paradise Lost" and its sequel, "Revelations," Berlinger and Sinofsky kept busy with side projects, ranging from television documentaries to Berlinger's flirtation with narrative in the ill-fated "Blair Witch Project 2." But it wasn't until the duo checked in with Metallica, whose music served as the score for the "Paradise Lost" films, that the filmmakers saw something that clicked not only professionally, but personally.

"We've been a partnership for a long time, you know?" said Berlinger. "And it was a little of a chill in our relationship, because we had some growing pains ... There's a certain magic when he and I come together on a project, and we took it for granted, frankly."

Robert Trujillo, the new bassist for Metallica, puts it accurately for both the band and the filmmakers when he says, "Here you have a rollercoaster that derailed for a few years, but it's back together again."

Sinofsky added, "The therapy probably bought Metallica another 10 years at least, and I'd like to think it also saved our working relationship, because you know, we're not that different from Lars and James on a certain level, because we're collaborators, and it really made a huge difference."

Ultimately, Berlinger and Sinofsky's collaboration with Metallica is a reminder that both the band and the filmmakers are true artists, despite those who may not pay enough attention to their brand of art. In the 1,600 hours it took to capture "Metallica: Some Kind of Monster," each transcends the medium to show what it means to be an artist and more importantly, what it means to be human.

"We were able to get rid of any anger or envy and just put things in the proper perspective," said Sinofsky. "Now I know we'll make a couple of more substantial films, if only we can find the right subject."

Log on to somekindofmonster.com to view the trailer to Metallica's "Some Kind of Monster.