The same day of his birthday, the widow Hobbs regrets not having children while offering some food to a beggar. After receiving the food, it becomes a magician who gives to the old uan seed from which a tiny Thumbelina is born. But Percival, pork confidence of the widow, is jealous and convinces a frog to kidnap the girl.
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 programme. Whereas Ottocaro Weiss means to represent the plague theatrically, what appears on stage is the scientific reality of the rat-borne infestation.