Daughters of Paris by Elisabeth Hobbes

A must-read for fans of Kate Quinn and Kristin Hannah!
Paris 1930s
A promise that binds them together. A war that pulls them apart.

Childhood companions Fleur and Colette make a vow, under the trailing ivy of their secret garden, that they will be secret sisters forever. But as they grow up, the promises of childhood are put to the ultimate test. For Colette is the daughter of the house, and her life is all jazz clubs, silk dresses and chilled champagne, while Fleur is the orphan niece of the housekeeper and doesn’t feel like she belongs anywhere.
Years later, in 1939, life as they know it will never be the same. As the German tanks roll in and Paris becomes an occupied city, the promise they made as children will have consequences they could never have imagined…