As D-Day approaches in Europe, the Allied command learns of a German staff conference to be held in Brittany at the Chateau de Voincourt, where the Nazis will discuss their Atlantic Wall defense strategy.
Foreknowledge of these plans could mean the difference between success and failure for the Allied invasion, and as luck would have it, the chateau happens to be the home of an undercover French Resistance agent, beautiful Anne-Marie Trevaunce, so there is every chance that the good guys will succeed in stealing them.
When Anne-Marie is incapacitated, luck comes to the fore once again: she just happens to have an identical twin sister living in England who is persuaded to take her place. Fortuitous turns are the norm in this improbable story, as cardboard heroes pull off miraculous rescues, double agents lurk everywhere and villains in uniform serve on both sides of the conflict.