During Friday’s opening-night performance, Megan Warren’s voice pierced the darkness to begin the Spotlight Theatre’s production of The Spitfire Grill, her immaculate a cappella vocals grabbing the audience’s attention before the music and lights even dared join her. Before her first song “A Ring Around the Moon” ends, you’ll be entranced by Warren’s depiction of Percy, if not for her plight of starting over after being released from prison. then because the folksy music so perfectly suits her voice.