In 1975, San Fernando Valley teen Joan Larkin reinvents herself as Joan Jett, a guitarist who wants to form an all-girl punk band. She pitches the idea to a sleazy manager, Kim Fowley, who pairs her with a drummer and then searches for a face: he finds Cherie Currie, at age 15, the perfect jailbait image for his purpose; by luck, she can sing. Two others round out the band, The Runaways. Fowley books a tour, signs them to Mercury Records, and packs them off to crowds in Japan. Seeds of conflict sprout early: Fowley puts Cherie front and center in the publicity, she’s soon strung out on drugs and vodka, and jealousies arise. Without adult supervision, where can Joan and Cherie end up?