Some call her America's musical conscience, others call her living history. Either way, Mavis Staples has been at the eye of multiple cultural storms, so when you put her in a tiny Chicago club with a stripped-down band, it's like cramming a hurricane into a phone booth -- utterly phenomenal. Singing like a preacher, Staples summons the Spirit on stage. You can hear it in the voluble audience, in the political and inspirational songs, in her anecdotes about the civil rights struggle. This is one fire time won't put out.