With the help of his assistant Anja, Ottocaro Weiss intends to put the plague on stage: circumstances beyond his control and a «lack of fresh talent» have forced him to close down his flea circus. For Weiss, the plague means the «extinction of everything that makes life miserable and low», and freedom along with it. Unbeknownst to him, he has won the support of a patron who is of the exact opposite opinion: for Johannes Wagner, the plague is an «organising principle», and, aided by his agent Moosbrugger, he is able to smuggle a new number onto the program. Whereas Ottocaro Weiss means to represent the plague theatrically, what appears on stage is the scientific reality of the rat-borne infestation. Wagner believes that he is doing a service to a super-civilized humankind by unleashing the epidemic, but he is foiled by Weiss, whose need to salvage his own personal credibility and regain the political dimension he had lost leads him to exchange the theatre's world of appearances for reality. In the end, the freedom afforded by the stage is merely an illusion, and is not enough.