Two girls growing up at Los Alamos in the 1940s gradually build a friendship against the looming backdrop of the war effort. Middle grade is where it's at, apparently. This is a sweet story that manages to touch on a lot of serious historical issues without ever losing its core emotional thread about found family and community. There was one bit at the end where drama was built through an unbelievable bit of miscommunication that I disliked, but otherwise it was note-perfect.