Satchit Puranik at a performance

You're seated in the audience, waiting for the play to begin. Except, there is no set. There is no director either. Nor has the piece been rehearsed before. Out walks a performer holding a sealed envelope. Inside that envelope is a script, one that the performer has never seen before. The script is riddled with blanks. Who has to help the performer fill in those blanks? You.