This snapshot of the evocative Indigo Girls catalogue treads over a decade of lilting folk, rootsy rock, and watertight indie, all held together by the interweaving of Amy Ray’s gravelly voice with Emily Saliers’ beatific tones. The Atlanta duo's most well-known tracks from 1987 and 1999 are all here (“Closer to Fine,” “Galileo,” “Shame On You”), but this collection is more than a greatest-hits set; it charts their evolution as a band, from purveyors of sweet harmonies and jangling guitars to a politically charged protest outfit.