The Killing Code reads really well! It's fast-paced, exciting, and set in the middle of a war. We have three things going on simultaneously, Kit's secret, some romance, and the murders of young women employed by the government.
Despite being for the war effort, this facility also seems to be a woman's haven. There is the freedom to work with other like-minded women, talk, even if some of them resent that for them, and dream about something better after the war.
While Ellie Marney wrote an excellent book, it's closer to three and a half stars than four for me. Someone with so much experience should have been able to pick up on certain things. For instance, while I loved Kit and Moya overall, sometimes I felt like Kit was snapped into becoming super flirty with Moya when the rest of the time, she came off pretty shy. I couldn't understand how her personality flipped in those moments. I also loved Violet and Dottie as characters, but I felt like Violet was used to superficially exploring race issues in the US. I think Violet was the only black girl we interacted with in the book, which is odd. Even worse when you realize that Moya was a supervisor who could have tried to at least foster more significant interaction between these units.
On the plus side, Raffi was fun, and I loved that he was quick to understand why Kit wasn't dancing. After Kit first suspected and dismissed, who she thought the killer was, I was sure it was that guy. Many misogynists hide like this, and we find out far too late. I did like how well researched the book was and Kit's secret. That added an absorbing layer to their actions and the risks involved.