Bletchley Park, 1942: As World War II rages on, Honey Deschamps sits at her type-x machine, tediously transcribing decrypted signals from the German Army, doing her part to assist the British war effort. Halfway across the world, Hitler's armies are marching into Leningrad, leaving a trail of destruction and pillaging the country's most treasured artworks, including the famous Amber Room-the eighth wonder of the world.

As reports begin filtering into Bletchley Park about the stolen loot, Honey receives a mysterious package, hand-delivered from a man that she has never seen before who claims that he works at the Park as well. The package is postmarked from Russia, and inside is a small piece of amber. It is just the first of several such packages, and when she examines them together she realizes that someone, relying on her abilities to unravel codes, is trying to tell her something.

Honey can't help but fear that the packages are a trap set by the authorities to test her loyalties-surely nothing so valuable could get through the mail during a time of war. And yet, something about the packages reminds her of stories that her brother used to tell her about her absent father, and when her brother is found brutally murdered on his way to visit Honey, she can't help but assume that the events are connected. But at Bletchley Park, secrecy reigns supreme, and she has nowhere to turn for help....