In a cabin in the woods, two bickering old Jewish recluses, Abe and Cohn, have retired, and haven't moved in two decades. Abe is a former stockbroker, and Cohn is an unemployed musician. In fact Abe and Cohn represent one character, that has been split into two opposing sides of the same spirit: Cohn is the realist, who believing only in empirical reality, Abe is the romantic. Miraculous events begin to happen. When Cohn wishes for a new roommate, his wish is promptly granted by the arrival of a mad magus named Wiseman. This leads to another visitor who is none other than
Joan of Arc, accompanied by her “Voices”. Though her arrival is at first greeted by a shotgun blast, Abe and Cohn are eventually charmed by the saint, and she gets them to re-consider many of their preconceived ideas to such an extent that Abe and Cohn eventually switch positions: Abe becomes the skeptical realist and Cohn becomes the true believer. She calls Abe and Cohn to join her in a space ship on a pilgrimage to Heaven — before the coming holocaust. Cohn is willing to go along, but Abe refuses, so Joan remains and sets up housekeeping in the cabin. When Joan accidentally cuts her finger in the kitchen, she faints and dies, which gets her to heaven without the space ship. Abe and Cohn are left behind to argue with Joan’s spiritual Voices. When Feiffer discussed
Knock Knock, he considered that aspects of it can be a metaphor for the post-1960s era America. “In the ‘60s there was an eruption of first rate social, political, cultural criticism that the country desperately needed.” He said, “The assumption was that all that had to be done was to show the people these things, and the country would change. … The full effect of all this exposure though was that instead of re-educating the country and making it ready for change, it terrified the country and made it withdraw from the idea of change.” When Joan arrives in the play, he added, “she comes in as the life-giving figure to bring hope. Because if those two men don’t change, they will die.” ==Production history==