If Massive Attack has a musical formula, it's one that's built around lulling you into a false sense of relaxed security, then turning the tables and plunging you into a nightmarish dystopia. The music is slow, creeping, subtle, dark, but ultimately — for all its dream-like qualities — it usually ends up being a cold harsh slap of reality.

Tonight, the Bristol, UK collective applies the same formula to its entire set. Two songs in, when Martina Topley-Bird comes out to perform “Babel,” the shadows are already present, but not to a degree that's disturbing the Rave Move 101 blissed-out dancers, or the abundance of weed-smokers currently nodding their heads along faithfully.

It's when the unmistakable vocals of reggae legend Horace Andy (introduced by Robert '3-D' Del Naja as “the original original, of all originals”) start ringing around this packed-to-capacity-arena for the mesmerizing “Risingson,” that this set takes a turn for the truly bleak.