Barely half of the Bomber Command's aircrews survive a full tour, but wireless operator Billy Angell has beaten the odds and completed his 30th - and final - mission. Now, Billy is due two-weeks leave, a posting to a training squadron and a six-month exemption from active duty. Except that MI5 need an airman to drop into Nazi-occupied France. MI5 are interested in Helene Lafosse, a frenchwoman keeping unusual company in her small family chateau in the depths of the Touraine. Helene has begun an affair with a senior Abwehr intelligence officer, who, in return, has turned a blind eye to the succession of Jews, refugees, resistance fighters to whom Helene offers shelter. It falls to Billy, playing a downed airman, to find Helene, to win her confidence and to plant a lie that will only make sense to her German lover. But this time, Billy isn't flying at 20,000 feet and he won't be able to escape the incendiary consequences of his actions.