World War II. Behind the horrific conflict known to all, there existed a secret war known to none. The war of codemakers and codebreakers. This is a story that unravels the lives of the men who vanished into the shadows of history.

The protagonist is a former codebreaker named Sakaguchi. In 1929 London, he is working a manual labor job when a mysterious man visits him. Through this visitor, Sakaguchi is forced to return to his old life and take on the task of cracking a specific, likely highly significant, cipher.

The narrative follows the lives of these shadowy figures, exploring the personal and professional challenges of those who create unbreakable codes and the equally brilliant individuals tasked with breaking them. The setting spans from post-World War I Europe in 1929 to the global conflict of World War II.

Written and illustrated by Kanji Shiba, the story is a seinen suspense manga serialized in Young Jump.