There are a few themes that you can explore but the main one of the novel is the innocence of childhood. Burno and Shmuel are both very young and do not really understand what is going on around them. They are completely innocent: Shmuel believing that his father is coming back and Bruno having no idea that his father is a Nazi commander and running a concentration camp in Auschwitz. Schmuel does not understand how critical his situation is not understanding that his life is on the brink of death. Neither child really understands that there is a war going on around them and that their innocence is about to be destroyed.