Sarah’s Key follows the two plots of Sarah Starzynski, a ten-year-old girl during World War II, as well as the life of Julia Jarmond in the present-day Paris. The stories are connected through the apartment Julia wants to buy, which happened to be the home of the young girl.
The French police came to the Starynski family’s doorstep on 16th July 1942 and arrested her and her parents before bringing them to a stadium filled with Jews. Before they were taken, the young Sarah locks her four-year-old little brother in a hidden cupboard, as she thinks that they will return to get him out later. She carries the key.
They are moved to another refugee camp, since the stadium was overpopulated, and Sarah and her parents are separated. Sarah tries everything she can to escape, and she manages to with the help of her friend Rachel and a man she knew from her old life. They are taken care of by an elderly couple, but as Rachel falls sick, the Nazi doctor arrests Rachel before she can escape, while Sarah hides. Later, Sarah manages to get back to her old apartment, and as she opens the closet, she sees her brothers dried corpse, still waiting for her in the closet.
In the present day, Jula Jarmond is planning on moving in to the apartment Sarah lived in during the World War II. She is a journalist, and she is asked to write an article about the Vel d’Hiv Roundup, as it is the 60th anniversary. As she researches, she finds out who the apartment belonged to. Julia learns about the whole story of the unfortunate Sarah, as well as finding out that she is pregnant. She divorces her husband, as she finds out that he had been unfaithful.
During her research of Sarah, she finds out that she had a son called William, but when she contacts him, he tells her to stay away. Sarah moves back to New York with her new-born baby, after William comes back to learn more about his mother. William also moves to New York, and shows Julia writings Sarah had made, and in the ending of the book, it is revealed that Sarah died by committing suicide
