In interviews promoting their 2005 debut’s release, Roll Deep were blunt about their ambition to take grime high into the charts. That aim is explicit in the blithe R&B of “The Avenue” but In At the Deep End isn’t simply about softening the UK underground’s edges. “Show You” cuts its rhythms and loops to the hypnotic stutter of alternative hip-hop while “Heat Up” and charged posse cut “When I’m ’Ere” are grime at its most captivating.