Three-year-old Tommy receives a book from his father, a painter, in which he has illustrated Tommy’s life. In a child's imagination, the train from his father's book becomes the number one enemy, which he must chase and fight to save his parents, pets, and the entire world. It is the same train that whistles in the courtyard outside their cell windows, taking people to an unknown destination. His dad, mom, and millions of others will never return. 

This film, intended for the youngest viewers, was created based on Bedřich Fritta’s unique book, which was saved from the Terezín ghetto after World War II. However, the book was only introduced to the public in 2013. It has been translated into many languages and serves as a sensitive educational resource for teaching about the Holocaust. Director Miloš Zvěřina obtained exclusive permission from the heirs to adapt the book into an animated film for young audiences.