After a failed attempt to defect Princess Mary, Team White Pigeon is captured by the Kingdom's Home Office. When the Duke of Normandy discovers that the girls are spies for the Commonwealth, he orders them to become double agents for the Kingdom. Princesses is placed under the control of the Duke of Normandy, and the other four spies are temporarily released while remaining under constant surveillance. Meanwhile on Control's side, this incident leads to suspicions that the members of Team White Pigeon have become double agents for the Kingdom. In order to investigate the matter, Control assigns the team a new mission.
