The boy in the striped pyjamas by John Boyne.
This is a very short and easy read, but also a powerful one. It is set in Nazi Germany where Bruno, a young boy, faces many challenges when his family move to live in the country, due to his fathers senior military position working at a concentration camp.
Bruno is oblivious to the horrors going on inside the camp and believes that the camp is just a game. He makes friends with a boy called Shmuel through the fence - the only person he now has as a friend.
This may be a short book but it certainly goes a long way and will leave you thinking even after you finish it. It will give you an idea of what a certain perspective of life was like in Nazi Germany. At least see the movie, which is exceptionally well done (despite the characters English accents). This story has a layered plot and will show you many things.