Hidden Letters is the real life story of an eighteen-year-old Dutch boy. The book is based on the 86 letters, postcards, and a telegram he sent to his family in Amsterdam while he was imprisoned in a Nazi labor camp in Holland. Philip "Flip" Slier´s letters, written in 1942, were discovered in 1997. His letters are supported with hundreds of other primary source documents, photographs, and maps that situate this young man´s experience in the context of World War II. Flip´s poignant writing shows the human side of war and reminds readers of the horrors of persecution and genocide.