One of the few indisputable geniuses of pop music, Sly Stone is a trailblazer and a legend. He created a new kind of music, mixing Black and white, male and female, funk and rock. As a songwriter, he penned some of the most iconic anthems of the 1960s and '70s, from "Everyday People" to "Family Affair." As a performer, he electrified audiences with a persona and stage presence that set a lasting standard for pop-culture performance.

Yet his life has also been a cautionary tale, kn...