This is a play shrouded in mystery. And the demand for secrecy comes straight from the playwright. It is a play that eschews the involvement of a director, of rehearsals and a set.
All we know about it is that after the third bell, the actor for that show (there's a different actor performing it every time) gets the script for the first time and has to perform. There is nothing between the actor and the audience - no directorial vision, no production design, no technical histrionics, all it has is a script - a strong (and complex) one - and an actor - a strong (and courageous) one.