The Dressmakers Secret by Lorna Cook.

Paris, 1941: As Coco Chanel’s assistant, Adèle lives side by side with German officers in the splendor of The Ritz hotel. But Adèle has a secret. She is working for the resistance, right under the German’s noses.

As occupied Paris becomes more and more dangerous, Adèle will have to decide if she can risk everything to save innocent lives and protect the man she loves…

Present day: Chloé’s grandmother has never spoken about the war and avoids questions about the legendary designer she once worked for. Now Chloé has come to Paris, to uncover the truth about Adèle’s life. But is she prepared for what she will find? And for the power of her grandmother’s secrets to change her family forever.
I love timeline books and this one has to be one of the best !
Adele & Chloe were great characters and as both stories played out , you really hoped the very best for them.
The author captured the feeling of fear and the history of Nazi occupied Paris and all the terror that must have been like to endure. Brilliant book..