The sound check

Before a concert there's always a sound check, with microphones passed from hand to hand and nobody paying much attention. 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

• Alípio, the sound engineer: He says 'one, two, three, sound' forty times a day. By the forty-first he says nothing.
• Bela, the support act: She opens the concert. She rehearsed the car chorus, just in case.
• Ciro, the new roadie: It's his first concert. He still thinks microphones have owners.
• Diolinda, the fan who arrived early: She's been at the gate since six in the morning. She watched the sound check as if it were the concert.