In the quiet cul-de-sac where Keith and Stephen live there is very little evidence of the Second World War. But the two friends suspect that the inhabitants of the Close are not what they seem. As Keith authoritatively informs the trusting Stephen, the whole district is riddled with secret passages and underground laboratories.

Then one day Keith announces an even more disconcerting discovery: the Germans have infiltrated his own family, and the children find themselves engulfed in mysteries far deeper and more painful than they had bargained for.