Sarah's Key by Tatiana De Rosnay

Julia Jarmond, a middle-aged American journalist living in Paris lives between two worlds. Although she hs been in Paris for 25 years nd married to a Frenchman for 17 years, she is still called the American by her in-laws. She and her husband are moving into an apartment owned by his family. At the same time, she is assigned to write a story about one of Paris' most shameful events, the Vel'd'Hiv, a rounding up of the Jews by Parisian police in 1942. Her research starts to bring to light events that her husband and his family want forgotten. 
Sarah's Key is a duel-timeline story covering Sarah's life in WW2 Paris and Julia's life in modern day Paris. The story is awesome covering an event I had never heard of. It is a must read. The only reason I gave it 4 stars instead of five was profanity and a few adult themes. Other than those items, I loved the book.