Curtis Booth, an out-of-work actor is hired to direct an amateur play. The play is terrible, and the actors are worse. Each rehearsal is worse than the one before. On opening night the set falls onto the actors. The audience thinks the collapsing set is intended. They see all kinds of symbolism in the accident.
The theatre wants Booth to direct another play. He still needs the money and figures the new play can't be worse than the one he just directed.
He is wrong about that.