Performing as the Bluebelles in the 1960s, Patti LaBelle, Nona Hendryx, and Sarah Dash wore bouffant wigs and chiffon dresses, and they harmonized vocals like many other girl groups of the era. After a decade on the Chitlin Circuit, however, they were ready to write their own material, change their name, and deliver--as Labelle--an electrifyingly celestial sound and styling that reached a crescendo with a legendary performance at the Metropolitan...