OR those who aren't in touch with the distinctive sound of heavy metal, it is an aggressive form of music, distinguished by its easily recognised facets. Guitars, especially, are commonly predominant, the lyrics involved best described as grave or dark.

Sam Dunn has been a heavy metal fan since he was nine years old. In 2000, while pursuing graduate studies in anthropology, he made the decision to explore the music's underlying culture.

Interested in learning why the genre was traditionally stereotyped, dismissed and condemned, the Canadian committed himself to a study of its heritage, eventually travelling the world to determine the answer. is the result, a collaboration between Mr. Dunn, Scot McFadyen and Jessica Joy Wise.

A brief summary of the film reads as follows: "Sam Dunn is a 30-year-old anthropologist. He's also a lifelong metal fan. After years of studying diverse cultures, Sam turns his academic eye a little closer to home and embarks on an epic journey into the heart of heavy metal.

"His mission: To figure out why metal music is consistently stereotyped, dismissed and condemned, even while the tribe that loves it stubbornly holds its ground, spreading the word, keeping the faith, and adopting styles and attitudes that go way beyond the music.

"Sam visits heavy metal landmarks as far-flung as L.A.'s Sunset Strip, the dirty streets of Birmingham, and the dark forests of Norway. Along the way, the two sides of Sam Dunn ? curious anthropologist and rabid fan ? collide, as Sam explores metal's obsession with sex, religion, violence and death, meets his heroes, and discovers some things about the culture that even he can't defend.

"Part social document, part celebration of a misunderstood art form, this documentary is the first of its kind ? a chance for metal fans to speak out and a window into a culture that's far more complex than it seems."

With anthropology the study of the physical, social and cultural development of humans, the fans, the music and the bands were all interesting subjects, Mr. Dunn said.

"I think the fact that metal is such a polarised force is why it's such a great subject for anthropologists. Everyone has a visceral reaction to heavy metal. You either love it or hate it and we start by investigating why that is, why it is such a divisive subject for people.

"Why it polarises people is because of the visceral nature of the music ? it hits you in the gut rather than the intellect ? but also because of the nature of the subject matter. Metal looks at death, religion, sex and violence and makes no bones in dealing with them in a loud and controversial way."

AS part of its exploration of the culture, the film also examines why it is predominantly male and its take on mainstream acceptance.

"Heavy metal didn't die in the Eighties," said Mr. Dunn. "If the master narrative about its history is that it's dead, Iron Maiden played its biggest concert in history in 2001 ? in front of a crowd of people who sang along to every lyric.

"The reason why it has such staying power is because it's an underground form of music. So if it becomes too mainstream, it retreats to where the core audience lies. So it never goes away it's just not televised on the video screen."

Mr. Dunn was initially interested in writing a book on heavy metal until Mr. McFadyen encouraged the anthropologist to make a documentary, believing it a more appealing medium for the project.

"The making of the film is a five-and-a-half-year story," said Mr. Dunn. "Scot's an old friend and at the time, he was doing the sound track for a film called which used a lot of heavy metal. He suggested I do a documentary and we investigated to see whether or not one had been done before. We found only parodies, comedies, movies like and ."

Mr. Dunn admitted his parents were initially a bit dubious about his decision to travel the world and record a history of heavy metal.

"I think at first my parents were probably sceptical - as all right-thinking parents would be," he laughed. "But when they realised I was serious and saw all the work that went into it, they became supportive."

Though not a huge fan of heavy metal at the time, Mr. McFadyen was excited by the film's potential and joined in on the project. The expertise he provided was considerable through his work as an assistant director on dozens of feature films and television projects including and the comedy hit .

In 2000, he combined his love of music and film to become a music supervisor and soundtrack producer and has since supervised a long list of projects including , , and . "I'm not a metal head but Sam has always been, since he was nine years old," he explained. "What drew me to it was that I felt all the representations of this culture were misrepresentations. They made people look like dunderheads, people who spent all their time head-crashing cans of beer. But I knew there was another world, a vibrant sub-culture, not just the one portrayed in . So we approached it historically and as an anthropological study. It was not until later, through conversations with Sam, that we decided to make it about his journey."

It took three years of fundraising before they could confidently move ahead with their plans. "Initially, we travelled to countries in Europe and North America because those were the countries where heavy metal originated and has very strong roots," Mr. McFadyen said. "Particularly in the United Kingdom and Germany, we felt it was important to lay the historical groundwork."

As part of their undertaking the men met with members of several heavy metal bands, whose opinions they sought out. By the end of filming, Black Sabbath, Twisted Sister, Iron Maiden, Alice Cooper, Cannibal Corpse, Steppenwolf, Kom, Girlschool, Mayhem and many other noted heavy metal groups had all added their input.

Mr. Dunn admitted it hadn't been an easy task to get the various bands to respond, many of them sceptical as to how they would be later portrayed.

"We were really persistent. We wrote a lot of letters. But it was really difficult to convince people to talk to us," he said. "Even the musicians assumed what we were doing would turn out to be something other than what we said. We were finally able to convince them with the help of Ron Smallwood, Iron Maiden's manager. He was very supportive. He said: 'You write the letters and I'll sign them'."

The end production pleased them all.

SAID Mr. McFadyen: "As a non-metal head I was surprised to find out how non-violent the community is. We went to a festival in northern Germany. On the surface it looked like a bunch of bikers but we got there and it was so peaceful. It was like being at Woodstock.

"There is a distinct difference between people who haven't seen the film and people who have seen the film. People who already have stereotypes, after the film they have a completely different perspective. I think, a more intelligent view.

"This is a music that's important to people. After it was completed, metal heads said thank you for our portrayal of them and non-metal heads were fascinated ? we met an 83-year-old Canadian guy who said he was going to go out and buy the music."

Added Mr. Dunn: "We're very proud fathers of this film. We worked hard and we're proud of it in terms of the response we've received ? from 80 year olds, from 16 year olds. The feedback from the festivals has been enormously positive and we feel particularly proud of the fact that people outside the culture are interested in it."