New York–based photographer Cat Jordan is ready to begin a new life with her successful, button-down boyfriend. But when she learns that she’s inherited the estate of a complete stranger—a woman named Isabelle de Florian—her life is turned upside down.

Cat arrives in Paris to find that she is now the owner of a perfectly preserved Belle Époque apartment in the ninth arrondissement, and that the Frenchwoman’s family knew nothing about this secret estate. Amid these strange developments, Cat is left with burning questions: Who was Isabelle de Florian? And why did she leave the inheritance to Cat instead of her own family?

As Cat travels France in search of answers, she feels her grasp on her New York life starting to slip. With long-buried secrets coming to light and an attraction to Isabelle de Florian’s grandson growing too intense to ignore, Cat will have to decide what to let go of, and what to claim as her own.