Spies - Michael Frayn

In the quiet cul-de-sac where Keith and Stephen live the only immediate signs of the Second World War are the blackout at night and a single random bombsite. But the two boys suspect that the comfortably ordinary houses in the Close and their inhabitants are not what they seem.

As Keith, the leader in all their enterprises, authoritatively informs the trusting Stephen, the whole district is riddled with secret passages and underground laboratories - hideaways for any number of murderers, unsung war heroes and secret agents.

Then one day Keith announces an even more disconcerting discovery: the Germans have infiltrated his own family. And when the secret underground world they have dreamed up emerges from the shadows they find themselves engulfed in mysteries far deeper and more painful than they had bargained for.