The Paris Secret by Natasha Lester

From the New York Times bestselling author of The Paris Orphan comes an unforgettable historical novel about a secret collection of Dior gowns that ties back to the first female pilots of WWII and a heartbreaking story of love and sacrifice.
England, 1939: The Penrose sisters couldn't be more different. Skye is a daring and brash pilot, and Liberty the one to defy her at every turn. Even if women aren't allowed in the Royal Air Force, Skye is determined to help the war effort. She's thrilled when it reunites her with her childhood soulmate, Nicholas. She's less thrilled to learn Nicholas is now engaged to an enigmatic Frenchwoman named Margaux Jourdan.
Paris, 1947: Designer Christian Dior unveils his glamorous first collection to a world weary of war and grief. He names his debut fragrance Miss Dior in tribute to his beloved sister Catherine, who forged a friendship with Skye and Margaux through her work with the French Resistance.
Present Day: Fashion conservator Kat Jourdan discovers a priceless collection of Dior gowns in her grandmother's vacant cottage. As she delves into the mystery of their origin, Kat begins to doubt everything she thought she knew about her beloved grandmother.