In it, a director and his aide rehearse for the opening of a new modernistic play, with an old man in darkness, the protagonist, by discussing the visual features of the man, noting visual changes, such as the directive "Whiten cranium."
They rehearse lighting - in total the play within the play is quite short, only a few seconds, from darkness, to the light falling on the man's head and then darkness again.
At the end of the play, the director notes "There's your catastrophe! In the bag." We hear the rising of the expectant applause on the opening day, with it fading out to conclusion.