and Dakota Fanning
whipped crowds into a frenzy at Joan Jett
's concert in Utah on Saturday when they joined the rocker onstage to celebrate their new movie biopic, The Runaways
star Stewart rocks out as Jett in the film, about the singer's 1970s band The Runaways, with Fanning portraying band mate Cherie Currie.
The actresses were the guests of honor at the Joan Jett & The Blackhearts
show in Park City this weekend and the I Love Rock N' Roll
hit-maker surprised fans by bringing the stars up onstage to thank them for their work on The Runaways, prompting the audience to break out into cheers and applause. Stewart and Fanning enjoyed the rest of Jett's concert backstage.
The Runaways premiered at the Sundance Film Festival on Sunday.
Image ©AP Photos
(This news article provided by World Entertainment News Network)