“Hall of the Dead” opens Isis’ fifth album, Wavering Radiant, with a slow, ominous sound as if signaling the start of a science fiction/horror movie, before the band kicks in forcefully. “Threshold of Transformation” concludes the disc with the same strategy in reverse, as the band’s stately hard rock suddenly gives way to a quieter, moody theme after more than nine minutes. And right in the middle of the album comes the becalmed under-two-minute title track, prefaced by more ambient music at the end of the first ten minutes of “Hand of the Host.” Thus there is a structure to Wavering Radiant, which is hardly a typical heavy metal album, even if it has many of the trappings of one. The raging guitars of Aaron Turner and Michael Gallagher are certainly typical of the style, as is the locked-in rhythm section of bassist Jeff Caxide and drummer Aaron Harris, while Turner alternates between normal singing and the sort of heavy metal growl that sounds like a wounded bear. (The vocals are mixed a notch or two below what would be required for there to be a chance of comprehending their meaning, another familiar metal procedure.) But a big difference is provided by keyboardist Clifford Meyer, who provides texture, filling up the overall sound and also adding ethereal touches that sometimes make Isis reminiscent of Pink Floyd, especially as the lengthy tracks stretch on into their seventh and eighth minutes. Wavering Radiant works as a single piece of music rather than a series of songs, and it is cohesively played by an ensemble that is more interested in the dark majesty of metal than its potential for expressing anger. – William Ruhlmann