This is the story of two teenage British boys in a Britain occupied by the Germans, which is what might have happened if the Nazis had successfully carried out their plans to invade Britain under Operation Sea Lion in the 1940s. Alan Mitchell and Sam Roberts study at St. John's Academy in the fictional Cambridgeshire market town of Hereward. Their Home Guard unit is defeated and the Schutzstaffel (S.S.) massacres the prisoners but the boys escape and return to German occupied Hereward.