Inside a former cotton-grading warehouse in Clarksdale, the audience is buzzing with anticipation for the evening’s show. It’s a routine Saturday (or Wednesday, Thursday, or Friday, for that matter) at Ground Zero Blues Club. The walls are plastered with old concert posters and heavily graffitied with signatures, and the patrons are as diverse as the international flags hanging overhead. Servers deliver baskets of hot tamales, catfish, and fried green tomatoes to tables cramped with mismatched chairs. Music lovers, young and old, have converged from all over the globe to this corner of Mississippi to hear the blues in the place it was born.