Creator of TV’s “Smash” and Pulitzer-nominated (Bad Dates and Mauritious), Theresa Rebeck takes us backstage and into the current phenomenon of stunt casting. That occurs when well-known stars are cast in roles over less well-known, but frequently more talented, stage actors. Conducting rehearsals of the star taking over the role being played by the unknown act is, arguably, the most important and overlooked player in the theater – the stage manager. That she also happens to be the understudy’s former fiancée only adds to the fun. Both witty and insightful, The Understudy opens a window to the world of theater rarely seen.