After the fall of the kingdom, everyone in England has divided themselves into thirty-nine communities, each based within a castle. This is the way people live now - in a future that seems like the past. Eleanor Conway was chosen to join the Castle Seven - the secret organisation charged with taking part in missions on behalf of the Clearheart Community. But Castle Seven is now Castle Six, following Anderson's dramatic departure. Anderson has kidnapped Eleanor's friend Mary and is holding her at Kinder Castle, a castle community run entirely by children. He tells her she's destined to be Queen of all England one day; but can she trust him? Hearing of her kidnap, and Anderson's plan to attack a neighbouring castle using his army of unruly children, Eleanor and the Castle Six make preparations for a rescue. But by the time they end their adventure, they're destined be one less in number.