Martin Scorsese's collaboration with composer Howard Shore may have tentative roots (the director dumped the late Elmer Bernstein's orchestral score for Gangs of New York in favor of a pastiche score with Shore's concert piece "Brooklyn Heights" at its core), but it's since blossomed into one of Hollywood's most rewarding, via The Aviator and this intriguing soundtrack for 2007's Best Picture Oscar winner. Essentially the introspective complement to the separately released, classic rock centered song-score that helps set the story's time and place, Shore's work here leans towards his own pop music roots (he was a member of '70s Canadian horn-rockers Lighthouse and the original musical director of SNL), seasoned with a brooding, contemporary edge. The score's innovative musical axis is a quartet of session guitarists whose disparate styles range from the elegant main theme tango (epitomized by the closing rendition of Marc Ribot and Larry Saltzman) to G.E. Smith's grittier electric blues and Sharon Isbin's quasi-classical stylings, often wrapped in a shadowy, electro-suffused soundscape that perfectly evokes the tale's undercurrents of betrayal and revenge.