This was one of the best books I've read in a long time. While the story involves magic, danger, and just a little dash of romance, it is presented in such a way that it seems within the realm of possibility. I loved that the action happened at the dawn of the Cold War era - not the usual setting for a young adult book - and was so neatly wrapped within the politics and events of the time that it could actually have happened in history. I also appreciated that the author took the time to explain some of the minor details of her thought process, rather than making the assumption that the reader won't notice the occasional hole. The illustrations at the beginning of each chapter also added to the charm of the book. 
 Well worth a read.