Autumn 1945 - Off the east coast of England, a Japanese sub surfaces, unloads its mysterious cargo, then blows itself to pieces.
Former spy Professor Tom Wilde is enjoying peacetime in Cambridge, settling back into teaching and family life. Until a call from senior MI5 boss Lord Templeman brings him out of retirement.
A nearby village has been locked down by the military, its residents blighted by a deadly illness. No one is allowed in or out.
There are rumours the Nazi machine is still operational, with links to Unit 731, a notorious Japanese biological warfare research laboratory. But how could they possibly be plotting on British soil - and why?
What's more, Wilde and Templeman's names are discovered on a Gestapo kill list. And after a series of assassinations an unthinkable question emerges: could an Englishman be behind the plot?
