Northern Soul is a cultural phenomenon twice removed from its original source in Britain in the late 1960s. Rooted in gospel and rhythm and blues music, with pounding "four-to-the floor" beats, it is often accompanied by swirling strings, vibraphone flourishes, and infectious clapping. Since the 1960s Northern Soul has spread globally, via the Internet and migration, to such unlikely places as Medellin in Colombia. By giving voice to the members of...