Although it contains about one hour's worth of music, Plague of Butterflies isn't a new album by Finnish doom sensations Swallow the Sun, but a stop-gap release pairing the previously unreleased, 30-plus-minute title rack with four demos dating from half a decade earlier. First a little backstory, though: after re-energizing the doom metal scene with three stupendous albums, Swallow the Sun's growing reputation apparently led to their being commissioned to score a project marrying heavy metal and ballet! But when said project was unexpectedly canceled, the group was left with a finished, three-part, 35-minute epic, about -- in their own words -- "an old hermit, deep woods, loneliness, and the plague," and nowhere to put it...until this release. Better yet, fans who may have worried that all this ballet business would produce a total aberration within the band's catalog can rest assured that, aside from taking as much time as they please to develop each musical theme -- whether crushingly metallic or delicately quiet -- all three suites boast as much dynamic and emotional range as the band's regular albums. If anything, the brutality is scaled up a notch, overall, with clean vocals taking a noticeable backseat to guttural growls, and the unleashing of a few blood-curdling shrieks that would honestly have scared those poor ballerinas right out of their tutus! In short, no need to fret, metal fans. And as mentioned above, the remaining four tracks -- "Through Her Silvery Body," "Out of This Gloomy Light," "Swallow," and "Under the Waves" -- are in fact 2003 demos that were sent out to only three record labels. All four wound up surfacing in slightly souped-up guises (i.e. -- enhanced with comparatively lush studio sound) on the band's immaculate debut from later that year, The Morning Never Came. And even though they'll certainly interest collectors on principle alone, their astounding qualities -- even in demo form -- are almost anticlimactic in their ready-for-primetime maturity. This band is just that good, and Plague of Butterflies is therefore another essential addition to Swallow the Sun's increasingly imposing discography.