In the quiet cul-de-sac where Keith & Stephen live the only immediate signs of the Second World War are the blackout at night & a single random bombsite. But the two boys start to suspect all is not as it seems when one day Keith announces a disconcerting discovery: the Germans have infiltrated his own family. & when the secret underground world they have dreamed up emerges from the shadows they find themselves engulfed in mysteries far deeper & more painful than they had bargained for.