The Civil Wars – the duo composed of singer-songwriters Joy Williams and John Paul White – played to a sold-out show at the Neptune Theater on Monday. They’re currently touring the US in support of their debut album, “Barton Hollow”, containing the breakthrough song, “Poison and Wine.” Prior to their set, the buzz around the theater was that it was Joy’s birthday. After taking the stage and singing their first few songs, the crowd reciprocated with a rousing rendition of “Happy Birthday” on Joy’s 29th.