England 1940: Paris has fallen to the Third Reich. Farmer John Cook and society heiress Lady Margaret are waiting for the day when German tanks roll across the green fields of their homes. Both are ready for the moment they will disappear into the woods and the fields to carry out their top-secret orders - to do whatever it takes to fight the Nazis once they arrive on British soil.

Their worst fears are realised when a parachutist drops from a German bomber during an air raid. Arriving at the scene, Cook finds the white silk hanging from a branch, and a mysterious crate containing a complex piece of machinery. The spy is nowhere to be found.

But at night, Cook and Margaret hear German voices in the darkness. Reports come in of others hearing similar things, and there are whispers of an agent from Berlin...

With enemies already hiding among them, how far will Cook and Margaret go to protect the country and the people they love?