The Measure of Gold by Sarah C Patten
No magic is more powerful or dangerous than the spell of love.
It is 1940, and Germany has just invaded France. Across the ocean, in Sweetwater, Tennessee, Penelope, a beautiful alchemist, receives a letter from her childhood friend, Naomie, urging her to France. Bereft from the loss of her widowed father, Penelope leaves her life and travels to German-occupied Paris. There, she meets Naomie’s brother, the brilliant alchemist Fulcanelli and his mysterious apprentice, Lucien.
Falling headlong into the alchemy’s esoteric world, she helps Fulcanelli and Lucien resist the Nazi forces.