Double agent. Double cross. Trained by the Americans. Trusted by the Nazis. One man holds the secret to the invasion of Normandy.

Code Name: Emerald

In preparation for Operation Overlord, the Allied invasion of Nazi occupied territory, the 'overlords' were the few Allied agents who knew the details of the operation. When one them is captured by the Germans, a double agent must infiltrate occupied Paris, with the help of a high level German officer and the French Resistance.