At first listen, you wouldn’t know that Mountain Meadows by Canadian roots-rock band Elliott Brood is based on a historical tale: The lyrics are as murky and cryptic as the disc’s Rorschach-like art. When you learn, though, that the album concerns the aftermath of the Mountain Meadows Massacre, a dark and deplorable 1857 incident in which Mormons and American Indians attacked a settlers’ wagon train in Utah, it makes sense: That’s why there seem to be spirits inhabiting this hauntingly beautiful music.