'Miss Sutherland ... what would you say if I told you I might be able to offer you a job helping the war effort?'

1943. World War II is raging across Europe and on the Pacific front. Kit Sutherland is hiding a huge secret when she is unexpectedly recruited to work as a young codebreaker at Arlington Hall, a US Signals Intelligence facility.

When Kit's roommate doesn't return home from a dance, it sparks a search that ends in a gruesome discovery. And soon it turns into a horrifying pattern: Government girls are being murdered in Washington, DC.

Kit joins forces with three other girl codebreakers, Dottie, Moya and Violet, and as they work to crack the killer's code, two things become terrifyingly clear: the murderer they're hunting is getting closer every moment ... and Kit's own secret could put her in more jeopardy than she ever imagined.