PARK CITY — The lead singer wears a dog collar. One of their first songs, "Thumb Hang," is about the Spanish inquisition. And the amplifier knob actually goes to 11.

In so many ways, the heavy metal band Anvil is indeed Spinal Tap (did we mention the drummer's name is Robb Reiner?).

But "Anvil! The True Story of Anvil," tracing the Canadian band's resolute determination in the face of countless setbacks, isn't really a rock 'n' roll comedy. Instead, this documentary, which was set to premiere Friday at the Sundance Film Festival, is an alternatively moving and hilarious love story — a tale of two people hopelessly devoted to playing heavy metal music.

Guitarist Steve "Lips" Kudlow met drummer Reiner in 1973, and four years later they formed Anvil. The late 1970s and early 1980s saw a gold rush of hard-core rockers: Scorpions, Iron Maiden, Whitesnake, Metallica, Anthrax and Motorhead among them. With its outrageous stage antics and pulsing rhythms, Anvil was right in the mix too, its album "Metal on Metal" envied by the band's head-banging brethren.

As a teen living in London, screenwriter Sacha Gervasi saw one of Anvil's first British gigs. "I was blown away," he recalls. "It was heavy music with really funny entertainment."

After meeting the band at an after-concert party, Gervasi showed Lips and Reiner around London the next day and soon thereafter was invited to be a roadie for Anvil's Canadian tour. "I would sit behind the drum kit every night, watch Robb play, and he taught me how to be a drummer," says Gervasi, who would later play with (and drop out of) the band that became Bush.

Gervasi went to college, his musical tastes evolved and he eventually came to Hollywood (where he co-wrote Steven Spielberg's "The Terminal"). But he never forgot the band — "I wondered what happened to my old friends" — so in the summer of 2005 he looked them up. Anvil had never made it — yet nearly three decades after they first joined forces, Lips and Reiner were still making music, trying to sell a few albums here and get a live gig there. "I thought they had split up," Gervasi says. "But I found out they were still going."

Lips was working at a food service company, Reiner in construction. They were in their 50s, their hair thinning, but their passion for music hadn't dimmed over the years. Having seen all of their contemporaries make it, Lips and Reiner weren't bitter — they were hungry. "I just kind of felt, 'I think there's a movie here,'" Gervasi says.

So Gervasi hit the road with Anvil again, collecting 300 hours of footage as the band launched a tour of Eastern Europe.

Tiziana, a girlfriend of the band's guitarist Ivan Hurd, organizes the tour, but her organizational skills are indiscernible: Train tickets aren't bought, plane schedules are mixed up and the band doesn't get paid. Ever. What is supposed to be the tour's highlight—an appearance at the Monsters of Transylvania rock festival in front of thousands of fans—turns instead into a cheerless appearance in front of 174 fans.

"It's been nothing but a nightmare," Lips says at one point. As the tour unravels, so does Lips and Reiner's relationship. But Lips bears no visible ill will. "I'm grateful," he says. "I don't regret a minute of it."

Back in Canada, the band tries to record another album, "This Is Thirteen," which will cost about $20,000 that neither Lips nor Reiner has. Having tried the patience of family and friends, Lips and Reiner must decide if it's finally time to call it quits or try one last time. "I need to realize this," Reiner says, "while I can." Says Lips: "I look at this particular chapter as my last chance."

Gervasi, who had never directed a movie, says he was unprepared for what he would eventually capture and how Anvil's story would unfold so much like "This Is Spinal Tap."

"On the second day of filming, my cameraman pulled me aside and said, 'Listen, you don't have to tell the rest of the crew, but you have to tell me: Are these guys actors?'"

Gervasi says that while the movie is doubtlessly funny, it's also a serious testament to believing in a dream. "Their dedication and integrity and commitment is without parallel," the director says.

In an interview, Lips says Gervasi's film is strangely affecting, especially when he sees rockers such as Motorhead's Lemmy, Guns N' Roses' Slash and Metallica's Lars Ulrich offer glowing Anvil testimonials. "To me, it's a little bit like I passed away and everybody celebrated what I did—but I get to witness it," Lips says. "It makes me feel great that I am getting the biggest respect from the biggest names in the business."

Gervasi brings "Anvil" to Park City not only in search of a theatrical distributor but also with the hope that his movie might somehow help Anvil realize its elusive wish for rock 'n' roll fame.

"We've made this movie, but no one has seen it, so nothing has changed for Anvil," Gervasi says. "The happy ending will be decided by the audience, and I'm hoping that even if people don't like their music, they will go on their Web site and buy their record."

Lips wasn't even sure he should pack his guitar for Park City, but he's hoping there's at least one more big live show ahead. "The centerpiece of it all is getting to play live—that's what it's all about," he says. "There's a reason actors like to do Broadway; it's instant gratification. And nothing surpasses that."