On their second full-length album, Chicago's Maps & Atlases defy easy categorization, choosing to walk their own incomparable musical path. Beware and Be Grateful sees the band's trademark experimentalism morphing to suit a more direct--though no less beguiling--songcraft. Fueled by a panoply of sonic influences, the album abounds with novel invention, spanning hymnal harmonies, percolating rhythms, even, in the case of centerpiece track, ''Silver Self,'' a full-on guitar solo (though to be fair, it's unlike any solo previously committed to wax).