A bold lead single featuring controversial Wikileaks figure Julian Assange is the kind of thing we'd expect from these hip-hop provocateurs. Not so expected? That the album it comes from is perhaps Calle 13's most introspective ever, in all senses -- from the confessional, highly personal self-reflection of tracks like "Adentro" to the general sense of impassioned quietude that pervades this relatively understated album. The fire-breathing duo still comes fast and furious with the rebellious spirit and political guests (Silvio Rodriguez, Tom Morello). It's just a more contemplative rebellion.