"People ask me every day where the real MCs is at. They're underground. There's mad-talented cats underground," announces Talib Kweli during the opening of Black Star's "Hater Players." And while a few multi-platinum MCs (OutKast, Lauryn Hill, Eminem) share a philosophy with hip hop's underground, it's difficult to argue with Kweli's assertion of the underground hip-hop scene's vitality. Just as back-to-basics, punk-informed guitar-rock bands once provided an alternative to what was being played on the radio and MTV, groups like The Coup and the Mountain Brothers and labels like Rawkus are laying down the antidote for mainstream hip-hop monstrosities like Puff Daddy and Master P. And while you'll never hear The Arsonists on lily-white alternative-rock radio, it's hard to deny that hip hop's underground is producing music far more progressive and challenging than the stuff that does get played. Like many of its peers, the group espouses a belief that hip hop's salvation can be found in its mythic pre-Chronic, pre-Puff Daddy past, when skills and lyricism and a sense of community were more important than criminal records or expensive videos. More importantly, it possesses the skills to back up its philosophy, spitting dense, polysyllabic, often funny verses over simple but inventive tracks. With a chemistry and lighthearted flair that at times recalls early Pharcyde, As The World Burns pays tribute to peers in the hip-hop underground on "Underground Vandal," engages in a lively round of dozens on "Lunchroom Take-Out," and lyrically flashes through three eras of hip hop on "Rhyme Time Travel." Boasting ambition, urgency, and conceptual smarts, As The World Burns is yet another reminder that vital hip hop is still being made; it just takes time and energy to seek it out.