A failed assassination attempt on the Kingdom of Albion's queen causes spies on all sides to be questioned on their loyalty to their respective alliances. Amid the increasing tensions, Ange le Carré, Dorothy, Charlotte, and Chise Toudou have returned with a new assignment: to collect an antique bookstore owner held captive at the kingdom's prison. However, this simple mission is soon followed by fear when Control assigns the team to investigate a suspected double agent within the royal family. Ange and the other members of Team White Pigeon must face betrayal and bloodshed as they attempt to make contact with another spy while aware of only one thing: their codename, Bishop.