Unfortunately-named only in hindsight, Boston-based post-metallers ISIS took the form pioneered by Neurosis and perfected it on their second full-length. It’s an impossibly heavy, impossibly immersive journey into the disturbing causes behind the narrator’s suicide. This 65-minute meditation drags the listener between emotional extremes, using the tried-and-true tension-release method of songwriting favored by their post-rock predecessors. Still, the devastating waves they unleash feel utterly gripping, never falling into the rote mechanics of some of their imitators.