In 1950, Billy Eckstine was one of the most popular singers in America. Movie-star handsome with an elegant pencil-thin mustache and a wide vibrato, Eckstine, the man known simply as "Mr. B.," possessed one of the most magnificent voices in popular music history. Born in Pittsburgh, Eckstine won a talent contest by imitating Cab Calloway and started leading jazz orchestras, calling himself Baron Billy. In 1939, he joined Earl Hines' orchestra, composing and performing the hits "Jelly, Jelly" and "Stormy Monday Blues." In 1944, he formed an orchestra that included, during its brief three-year run, the greatest stars in bebop, including Charlie Parker, Dizzy Gillespie, Miles Davis, and Sarah Vaughan. Signing with MGM, he rose to superstar status, sold millions of records, marketed his own line of "Mr. B." shirt collars, and inspired an army of female admirers, known as "Billy Soxers."

Eckstine fought all his life for recognition and respect in his quest to become America's first black romantic singing idol, but he faced hardships in the segregated music world of the '40s and '50s. Despite this, he went on to influence many singers who followed, including Arthur Prysock, Johnny Hartman, Johnny Mathis, Kevin Mahogany, Barry White, and even Elvis Presley. Mr. B examines the life of one of the twentieth century's most amazing success stories, from his early days in Pittsburgh to his time in Las Vegas.