The doc includes interviews with musical legends Bruce Springsteen, Stevie Wonder, Mick Jagger and Sting, who pay tribute to the singers who often spent decades supporting their stellar careers. The film focuses on the women who made up their background choruses, and what their varied careers have held for them since. Their stories are heartbreaking: Phil Spector imprisoned and stole Darlene Love's great talent, and one after the other strove to break out on their own. What kept them back? The youngest of the women, Judith Hill, is trying to buck that trend.