December 1939. Germany and Great Britain are in the fog of the phoney war. The First Sea Lord Winston Churchill knows that England is not ready for the fight, she could lose against the might of Germany. Four British spies have perished in strange circumstances in Nuremberg trying to discover the biggest secret of the Third Reich. Churchill turns to the only man he knows who can solve the mystery. But Sherlock Holmes is now 83, Dr Watson even older. They must cross the Channel, pretending to be German sympathisers. If caught, England will disown them. Holmes accepts the challenge; indeed he has been awaiting the call. They will solve the mystery, or die in the attempt. Two ancient men of England and one beautiful nurse enter enemy territory. Their loyalty will be tested, more than once, and there is absolutely no one they can trust. The secret of Nuremberg is more sinister than even Holmes could imagine.