Meet the Williamson sisters, Britain's most treasured World War II veterans. Now in their nineties, Josephine and Penny are in demand, popping up at commemorative events all over the country. Despite their age, they're in great form-sprightly and sparky, and always in search of their next "excitement." This time it's a trip to Paris to receive the Légion d'honneur, accompanied by their devoted great-nephew, Archie.

Keen historian Archie believes his great aunts had minor roles in the Women's Royal Navy and the First Aid Nursing Yeomanry, but that's only half the story. There's a reason sweet Auntie Penny can dispatch a would-be mugger with a brolly. This trip to Paris is not what it seems either.

Scandal and crime have quietly trailed the sisters since the war. Now armed with new information about an old adversary, these much decorated (but admittedly ancient) veterans intend to settle scores, avenge lost friends, and pull off one last heist before the curtain comes down on their illustrious careers.