Once is a heartbreaking, beautiful story about a young, innocent Jewish boy named Felix. Before WWII began, his parents hid him in a catholic orphanage where the nuns kept his secret. After four years at the orphanage, Felix is sure that he's received a message. He believes that his parents want him to come and find them. So he sneaks out of the orphanage and finds his old house above his parent's bookstore. But his parents are no longer there. As he walks around trying to find his parents, he learns more about the war, who the Nazis are, and meets a little girl named Zelda whose parents were killed. This is an innocent, childlike account of WWII. I would recommend this book to 6th grade and older, seeing as it is about one of the most terrible wars in history. It is sad, scary, and sweet, and you will definitely cry your eyes out!