The story is set during the Second World War and deals with a group of children living in the North East of England in a town called Garmouth regularly suffering from bomb attacks by the German forces. One of the children raids a German aircraft that crashed in the area and takes a fully operational machine gun, intending to set up their own fortress. They fire the gun at a German plane, missing it but forcing it to crash-land; the gang befriend the pilot, not knowing that they had caused him to crash. The book explores the impact on the community of living under war conditions, and probes the deep effects on the children of that community. Their play reflects the terrors, paranoias and anxieties which were part of 1940s Britain.