Interesting look at the female code breakers in America during World War II, although it focused far more on the mystery and the relationships between the women than the historical angle. The characters felt two-dimensional, but at the same time, their relationships were well sketched out and felt more vivid than the characters did individually. I read the whole thing in a day, mostly because I really wanted to figure out who the murderer was. It was an obvious choice in hindsight, but there were a few possible suspects along the way.