'' Once '' is a 2005 children 's novel by Australian author Morris Gleitzman . It is about a Jewish boy named Felix , who lived in Poland , and is on a quest to find his book-keeper parents after he sees Nazis burning the books from a Catholic orphanage in which he stays . He finds a girl called Zelda in a burning house with her dead parents — he takes her with him and protects her from confronting her parents ' death by telling her stories . Although '' Once '' is a work of fiction , Gleitzman was inspired by the story of Janusz Korczak , the events of World War II , and Hitler 's attempt to exterminate the Jewish population of Europe
exterminate the Jewish population
The Holocaust
Once (Morris Gleitzman novel)