Britain is at war and a secret arm of the British government called the Ministry of Unladylike Activity is training up spies. And who better to become a spy than a child? A child can go places, see things and listen in on conversations in a way that no adult ever can. Enter May Wong and her friends. Trained up at the Ministry, they soon embark upon their first mission: masquerading as evacuees, they are sent to a wealthy manor house to spy on the owner, who is suspected of working for the enemy. And then the murder happens....