The Green Glass Sea by Ellen Klages, published by Recorded Books, 2007.
But, back to the story (a finalist for the Quill Award and winner of many state awards). The alternating point-of-view of two girls from very different backgrounds thrown together at Los Alamos during World War II provides the reader with a more complete picture than could be achieved with just one narrator. The vivid descriptions create a spellbindly complete world for complete reader immersion.
I've not yet had a chance to read Klages' sequel, White Sands, Red Menace but I look forward to it.