In the early 20th century, the discovery of the substance Cavorite enabled the creation of advanced military technology and pushed the nation toward conflict. London is now split by a wall, with the Kingdom and the Commonwealth of Albion engaged in a silent war where espionage serves as the sole weapon capable of destabilizing the enemy. A group of girls from the prestigious Queen's Mayfaire school operate as undercover spies for the Commonwealth. Under the leadership of Dorothy, an experienced driver with a striking personality, the team features the talents of Ange le Carré, a cold-blooded liar and expert sharpshooter; Chise, a skilled samurai; and Beatrice, a voice-mimicking specialist. They employ their distinct individual abilities to help the Commonwealth survive in a dark world rife with conspiracy, mystery, and infiltration. Amid the shadow of war, they hold only one objective: completing their mission.