A botched assassination attempt on the Queen of the Kingdom of Albion leads to spies on all sides being questioned regarding their loyalty to their respective alliances. Amidst the rising tensions, Ange le Carré, Dorothy, Charlotte, and Chise Toudou return with a new assignment: to retrieve an antique bookstore owner held captive in the kingdom's prison. However, this straightforward mission is soon overshadowed by fear when Control tasks the team with investigating a suspected double agent within the royal family. Ange and the other members of Team White Pigeon must confront betrayal and bloodshed as they attempt to make contact with another spy, knowing only one thing: their codename, Bishop.