The author's mother spent five years in seven work camps, and managed to save letters and other personal papers and artifacts at great personal risk. She survived the war and only came forward with this treasure trove of documentation after a health scare, when she gave them to her daughter (the author) and opened up about her experiences.
The letters and the book that presents them perfectly displays the human side of the Holocaust, showing people's emotions at having a loved one be imprisoned, and be cut off from family and loved ones. It's an important story, and an often overlooked aspect of the Nazi machine. Recommended.