Noises Off," "the classic farce by the Tony Award--winning author of "Copenhagen, "is not one play but two: simultaneously a traditional sex farce, "Nothing On, " and the backstage "drama" that develops during "Nothing On"'s final rehearsal and tour. The two begin to interlock as the characters make their exits from "Nothing On" only to find themselves making entrances into the even worse nightmare going on backstage. In the end, at the disastrous final performance, the two plots can be kept separate no longer, and coalesce into a single collective nervous breakdown.