Wow. I finished this one in record time, after hearing about it for months and months. I knew what the key was about, but the "event" happened half-way through the book, and I couldn't imagine what the rest of the book would be about. Again, wow.
I don't want to give too much away, but the gist is that a Jewish family living in Paris is rounded up by the French police (in collaboration with the Nazis). The secret to the key is heart-breaking, but that is only part of the story. The very ending was just a little too pat for me, but it's still an excellent Holocaust novel. This would be a great one to use with students--I already use The Book Thief with my Honors freshmen and Parallel Journeys with the Honors sophomores. Like Parallel Journeys, this story shows us another side of the Holocaust--it wasn't just Germany and the Nazis.