When a British RAF Whitley plane comes under fire over the French coast and is forced to drop their cargo, a spy messenger pigeon finds its way into unlikely hands. The occupation has taken much from the Cotillard sisters, and as the Germans increase their forces in the seaside town of Boulogne-sur-Mer, Gabriella, Martine and Simone can't escape the feeling that the walls are closing in. Yet, just as they should be trying to stay under the radar, Martine's discovery of a British messenger pigeon leads them down a new and dangerous path. Gaby would do anything to protect her sisters but when the pianist is forced to teach the step-daughter of a German Commandant, and the town accuses the Cotillards of becoming 'Bad French' and in allegiance with the enemy, she realizes they have to take the opportunity to fight back that has been handed to them. Now, as the sisters' secrets wing their way to an unknown contact in London, Gaby, Martine and Simone have to wonder - have they opened a lifeline, or sealed their fate?