Unlikely rock success story System of a Down launched a brief guerilla tour Monday (4/25) in San Francisco to hype their highly anticipated "Mezmerize/Hypnotize" album project, playing a frenzied 90-minute club set that touched on material from throughout the group's seven-year career.

The show at The Fillmore opened with the new single "B.Y.O.B.," and its chorus, "Everybody's coming to the party/Have a real good time," seemed to be taken literally by the crowd. But like most SOAD songs, the hook is the sugar that delivers tough medicine--in this case an anti-war message: "Why don't presidents fight the war?/Why do they always send the poor?"

SOAD has become masterful at this slight of hand, getting their highly political messages across by mixing breakneck, hardcore beats, slowing down into a brief melody, and cranking right back up again. In concert, it's evident that the spot-on rhythm section of Shavo Odajian and John Dolmayan is the engine that makes this formula go. It's also clear that the fans are listening to the lyrics, because, at times, the crowd's sing-alongs top the volume of the music coming from the stage.

When the band launched into its best-known song, "Chop Suey," the crowd jumped up and down in unison, testing the structural stability of this historic club's hardwood floors. And, for much of the night, a good 25 percent of the floor was claimed by slam-dancers in the pit.

System of a Down's Serj Tankian isn't your typical frontman. He's got the requisite lanky physique, but his slightly awkward movements on stage, along with his mop of curly hair, evoke '80s-era Howard Stern more than Robert Plant. Nonetheless, he's the perfect voice for this group, able to deliver a death-metal chant before switching into theatrical vocal sections that conjure Freddie Mercury.

Though his bandmates are all business on stage, guitarist and principal songwriter Daron Malakian--in between his scattershot licks--is the SOAD member most likely to smile, and to interact with the crowd.

"We're here to kill rock and roll," Malakian said at one point during the set. But the truth is, this group of Armenians from Los Angeles is one of a handful of popular rock acts with the stuff to save it. Their upcoming "Mezmerize" album is due May 17; its companion set "Hypnotize" will hit stores sometime in the fall.

Sure, they're prone to a few Spinal Tap-ish excesses--some of their pseudo-Middle Eastern vocal exercises border on the ridiculous, and a few extended instrumental sections come across as Bollywood soundtrack fodder--but rock and roll is all about excess, as proven over and over again by System forefathers like Queen and Led Zeppelin. Not being afraid to sometimes look silly is half the battle.