The Julie Ruin knows what love is: It's Kathleen Hanna The audience packing the Black Cat's main stage Saturday night ranged rather remarkably in age: from grizzled and gray-bearded to fresh-faced and screaming. The collision of generations was occasioned by a performance from the Julie Ruin, a project conceived more than 15 years ago but only now playing shows and behaving like a fully functioning band. And while the quintet did play an engaging set chock full of ringing punk choruses and squiggly keyboards, the evening really felt like a re-coming-out party and celebration of its founder and leader, Kathleen Hanna. Hanna - best known for fronting 1990s bands Bikini Kill and Le Tigre as well as being an inspiring feminist activist - titled her under-appreciated 1997 solo album "Julie Ruin." It was during a long struggle with illness (finally correctly diagnosed as late-stage Lyme disease in 2010) that she pondered using that name for a full-fledged band. With Bikini Kill bassist Kathi Wilcox as anchor, Hanna added guitarist Sara Landeau, drummer Carmine Covelli, and singer and keyboardist Kenny Mellman. With a new record released Tuesday and a set of tour dates this month, the group has fully stepped into the limelight. The hour-plus performance was a lively mix of recent songs and tracks from the 1997 album, whose arrangements were given bristling updates. Hanna's voice sounded strong on older songs like "V.G.I." and "Breakout A-Town," and though she gulped water throughout the set, she hardly looked like someone battling a long-term illness. Mellman served as comic foil and vocal partner - and the intertwining of his husky bellow and her siren wail cast Hanna's melodies in an arresting light. Among the new songs, "Goodnight Goodbye" and "Run Fast" stood out, solid mid-tempo creations that allowed Hanna to jab words into the sinewy punk grooves. But "Oh Come On" was the evening's highlight: a strutting backbeat and chunky guitar riff supporting flitting background vocals and a snarling lead. It was where the band sizzled - and demonstrated its potential. As with any event in which Hanna has a microphone, her comments were by turns hilarious and gripping. She touched on motivation for her new songs, on her illness, on yoga, on opening band Swearin" (who played a sterling half-hour set); and she seemed genuinely touched by the sold-out house and the wildly enthusiastic reaction to her songs. She closed with an apology to a particular audience member: a former classmate whose nose she had punched and bloodied in the fifth grade. Whether he took her up on her offer to shake hands after the show is unclear, but as an offer to tidy up the past and move forward, it was a fitting capstone to a memorable evening. Foster is a freelance writer.