Occupying a self-defined niche in contemporary music, Massive Attack have, for the past dozen years, functioned as both the standard-bearers and genre-breakers for trip-hop. Though that genre has certainly worn itself down to a nub thanks to the diluted sounds of numerous come-latelys, each new record by Massive Attack has been a revelation. Though the claustrophobic freneticism of 1998's "Mezzanine" (the group's third proper album) might have indicated a dark night of the soul, the hazy beauty of its follow-up, "100th Window," easily elucidates the fuzzy pleasure of waking up the next day to a dewy sunrise. Eschewing much of the dubby thump that defined their first two albums, as well as the electronic buzz that ran through "Mezzanine," the group relies largely on delicate atmospherics and numerous, subtle touches to create a mood that is simultaneously stark and gauzy. That effect is accentuated by woozy vocal contributions from Horace Andy and Sinead O'Connor (whose voice is amazing on the three tracks she assists on). Utterly abandoning preconceptions of where his group fits, mainman Robert "3-D" Del Naja has, with "100th Window," pushed Massive Attack beyond mere innovation and into an orbit all their own.