The music doc has long settled into a format: uncritical interviewees, archive footage, rise, fall, difficult comeback. But this one finds a terrific subject in Kathleen Hanna, the smart, dynamic, confrontational co-founder of the 1990s Riot Grrrl movement and lead singer of Bikini Kill and Le Tigre. Fusing punk spirit with feminist anger, she elbowed out a space for women in the macho moshpit of 90s grunge, in which she rocked out with an energy that's still beguiling. She's a real role model, and her mysterious withdrawal in 2005 – explained as due to undiagnosed Lyme disease – left a vacuum that's still conspicuously unfilled.