She asked nicely

She asked for the microphone. Nobody answered. At a concert, silence means yes, and the microphone changed hands. Four people and one microphone: one person per row, one per column. Whoever is left alone with it in the same room is the one you're looking for.

Suspects

• Adelaide, the front-row fan: She's been in the front row since six in the morning. She knows all the lyrics, even the ones not written yet.
• Bruno, the roadie: He runs cables, plugs in speakers and hands microphones to anyone who asks with conviction.
• Cátia, the radio producer: She has the list of who's allowed on stage. The list was left in the van.
• Diogo, the singer's manager: He swears he'd never seen the woman and that she wasn't with his crew. It's a start.