One of the best children's stories I've ever read. I felt the two female protaganists were really well drawn and believable. I also felt that the author did a great job evoking a social history of what it might have been like to live at Los Alamos during World War II. The bits of history and scientific information blends seamlessly into an elegantly told, truly interesting story.

I really loved it.

Also, I should mention that the audio book narrator for this particular title was great. I highly recommend getting this as an audio book if you are so inclined.