When bands sign to a major label, their music sometimes becomes more mainstream. Not Mastodon.

Blood Mountain, the group's third album, their first for Reprise Records isn't just unconventional, it's surreal, progressive and unrepentantly heavy. Instead of writing songs for rock radio, Mastodon drew inspiration from within, combining their favorite musical styles, including thrash, doom, prog and psychedelic metal to concoct something utterly original, undeniably devastating and irrefutably entrancing .

"This album is a nice collaboration of everybody's character and individuality," says singer and bassist Troy Sanders. "I always felt we were four unique individuals making up the band, and we've combined to make a meal with wicked ingredients. But most important, everything we do is completely pure and honest."

"The Wolf Is Loose" starts as shouty crust punk, then lunges into a futuristic metal passage before tumbling into a driving doom riff and a booming vocal harmony. "Crystal Skull" progresses from a sinister lick reminiscent through a frantic series of chugging rhythms, angular lines and off-kilter beats. And "Colony Of Birchmen," which features Queens Of The Stone Age frontman Josh Homme, wraps chunky guitars and ethereal arpeggios around moody melodic vocals. Other songs also showcase guests; Mars Volta frontman Cedric Bixler appears on "Siberian Divide" and Ikey Owen plays keyboards on "Pendulous Skin."

The music of Blood Mountain isn't all that separates Mastodon from the hordes of trendy metal bands. The lyrics are also pretty out there. Like Mastodon's remarkable 2004 record Leviathan - which earned Album of the Year honors in Revolver, Blood Mountain is a brain-teasing concept album. But while Leviathan was based on Herman Melville's 1851 novel "Moby Dick," Mastodon hatched the multi-tiered plot for the new album out of their own demented minds. The disc tells the story of a quest to ascend Blood Mountain to find a crystal skull, reach the top and insert the skull inside the bandmembers' own heads in order to eradicate "reptile brain" and transport them to the next phase of human evolution. Of course, the trek is far from simple.

"Pretty much anything that can happen on a mountain does," says drummer Brann Dailor, who writes the lyrics along with Sanders and guitarist Brent Hinds. "We get lost, face starvation, have to kill our own food and eat it. We get trapped in an avalanche and we meet all these creatures along the way." Ah, the creatures, the inhabitants that make Mastodon's journey so treacherous - and so cool. In "The Wolf Is Loose" the guys almost die fleeing a ravenous wolf, then during "Colony Of Birchmen" they come across a race composed of small tree people who link together to form a single, giant treeman, while in "Circle Cysquatch" they bump into a species of one eyed yeti. But just when they think the Sasquatch will tear them apart and eat them, the beasts show compassion and intelligence. "It turns out they're wonderful, loving creatures, and they give us guidance and mental power," Sanders says.

If it seems like the members of Mastodon have been watching too much "Lord Of The Rings," take note: Their journey up Blood Mountain was as inspired by their counter culture lifestyle as by their DVD collections. And the phantasmagoric quality of the expedition parallels some of the strange dreams they've had and states of consciousness they've experienced in their own lives. "I wanted it all to be kind of acid trippy," Dailor says. "In one part, there are lines about chewing up different roots on the mountain and hallucinating, and things kind of get messy from there."

"In 'Siberian Divide' we get trapped under a bunch of snow from a sma ll avalanche and then our bodies encounter brain freeze and we trip the fuck out," elaborates Sanders. "We think our wrists are food and start to gnaw on our own wrists for the little bit of warmth that's left inside, ultimately bleeding to death."

Psychedelic imagery notwithstanding, Blood Mountain is ultimately a metaphor for the obstacles and triumphs Mastodon have encountered since they began their musical crusade. The band formed in 1999 shortly after ex-Lethargy and ex-Today Is The Day members Dailor (drums) and Bill Kelliher (guitar) moved from Rochester, New York to Atlanta. One night, during a High On Fire show, the two met ex-Four Hour Fogger bassist Sanders and guitarist Hinds and started talking underground metal.

"We were all familiar with each other's histories," says Sanders, "because we were fans of Today Is The Day. And Bill had seen our band play opening for Neurosis when he was visiting Atlanta in '98. They said they needed a second guitar player and a bass player to form this new band, and we were like, 'Well, hey, dude, here we are. Hell, yeah.' Two or three days later, we were down in the practice space making a racket just to see if the vibe would gel, and within five minutes it felt like a done deal."

Mastodon recorded their first demo in June 2000 and played numerous dates with bands as far ranging as Cannibal Corpse, Queens Of The Stone Age and Morbid Angel. The crushing demo and powerful live shows earned them a record deal with Relapse records, and in August the band released its debut EP Lifesblood. Technically complex, rhythmically pummeling and instilled with groove, the disc earned Mastodon a loyal following even if it didn't exactly pay the rent.

"Man, I lived on a couch with Bill and Brann for the first two years of the band's existence and we toured like crazy," Sanders recalls. "We lost money out the ass and yet we were all fueled with this fire to continue. There was something embedded in the back of our brains that knew we had to give this a full-on shot because it might pan out."

In October 2001, Mastodon entered the studio with producer Matt Bayles to record their full-length debut, Remission. The album came out in 2002 and its striking blend of stoner metal, hardcore, prog-rock and, southern rock set the metal world ablaze. But it was the raging turmoil and pulverizing elegance of 2004's Leviathan, again recorded with Bayles, that made Mastodon one of the most lauded new groups. Revolver called them one of the 25 Greatest Live Bands Ever and Metal Hammer declared them a group you "Must Hear" and Kerrang labeled them "Best Band On The Planet." It wasn't just metal fans that felt the love. Alternative Press named them one the "25 Most Important Bands in Metal" and they were even profiled in Rolling Stone.

After playing Ozzfest last year, Mastodon started working on songs for Blood Mountain. They wrote tirelessly for five and a half weeks, about two weeks longer than they had to write Leviathan. The extra time gave them the luxury to demo the songs before they recorded them - something they'd never had the chance to do - as well as experiment with different techniques that give the songs extra flavor and texture. "Circle Cysquatch" features a harrowing vocoder voiceover, "Bladecatcher" includes squelching vocals that sound like an angry R2D2 and "Crystal Skull" opens with tinny tribal clatter before thundering into the opening riff.

"I did that on a 50 gallon drum I saw around the corner from the studio," Dailor says. "There was a dude working on his car there in the street, and he had two of these 50 gallon drums. So I asked him if I could borrow them and he said I could as long as I promised to bring them back. So I recorded 12 tracks of this Middle Eastern sounding thing and it was awesome."

Mastodon recorded the album with Bayles from the middle of Febr uary until the beginning of April before Rich Costey mixed the disc. Again, it was more time than they'd ever had, but this time there were the added pressures of living up to their own legacy, and it never felt like there were enough hours in the day.

"We sat and listened to everything at the end of every day and talked about how the songs were coming along and what we wanted to change," Sanders says. "After a while, I kind of felt like the world was on our shoulders. We just wanted to make the coolest music possible and make sure it was as awesome as it could be - make sure every riff, every note, every drumbeat was in the perfect spot."

In the end, Mastodon crafted an album that's musically sophisticated yet primal, a disc where every new passage, regardless of how slow or fast, leads to the culmination of an epic adventure. And the diversity is astonishing. "Capillarian Crest" alternates between jazzy tendrils and moshpit-rattling ferocity, sounding like a fierce amalgam of Motorhead, King Crimson and Rush, "Hunters Of The Sky" is a surging, off-kilter race with drums as tumultuous as Keith Moon and "Pendulous Skin" is expansive and celestial, with guitars reminiscent at times of Deep Purple and Pink Floyd.

"I really wanted to do guitar cartwheels and finger gymnastics on this record," says Hinds. "There are more solos on this than any other Mastodon album, but every part, no matter how complex, is there for a reason. We just really went for it more than we've ever done."

In addition to challenging instrumental passages, Blood Mountain features vocals that range from melodic conversations to raging diatribes. "We're all smart enough to know that we don't have to scream our brains out every second for the whole album," Sanders explains. "That's just not where we want to go as we expand and further our catalog of music. Overall, there was just more room and more potential for various vocal sounds on this album. And we're not at all apprehensive about doing it because we don't feel like we're cheesing out or doing anything wrong."

With the release of Blood Mountain, Mastodon have reached the top of a peak, from which they can see other, even higher mountains before them. And that's where they're headed next. Regardless of how many cover stories or awards they receive, Mastodon are driven by the need to ascend the mountain, implant the skull and ascend to the next level of evolution. It's not that they're unappreciative of the accolades, they're just too busy focusing on the next project to stop what they're doing.

"When we started, we never imagined getting to where we are today," Sanders says "We're so grateful and we appreciate everything that's been said about us. This has all been unreal. I never thought we'd do major tour support for Iron Maiden in Europe or be on a major label or be on our fourth tour with Slayer, or be ranked as having one of the Top 10 albums of the year in any magazine. It's all been part of this crazy journey that we've lived, and we'll keep rolling forward. We feel like we've still got so far left to go."