What is the author's tone in Five Chimneys: The Story of Auschwitz by Olga Lengyel?

The story has dark overtones but there is a subtle undercurrent of hopefulness that pervades the writing. It seems that Olga's personal method of coping could have been the same other victims of horrendous crimes report in that she seems almost to be reporting what she saw rather than what she personally witnessed. This impersonal approach is likely a self-preservation mechanism that arises from her strong resolve to survive in order to tell the world what happened at the hands of the German soldiers.