Eva Traube Abrams, a Florida librarian, is at the returns desk one morning when her eyes lock onto a photograph in a newspaper nearby. She freezes; it's an image of a book she hasn't seen in sixty-five years---one she recognizes as the Book of Lost Names. The religious tome in the photograph, a French text thought to have been stolen by the Nazis, contains a mysterious code that researchers can't decipher. Only Eva holds the key---but does she have the strength to revisit old memories and help reunited those parted in wartime?
In 1942 Eva escapes Paris after the arrest of her father, a Polish Jew. Finding refuge in a mountain village in the Free Zone, she learns to create false identity documents for Jewish children fleeing to neutral Switzerland. But erasing people comes with a price, and with the help of a Resistance forger named Rémy, Eva finds a way to preserve the real names of the children too young to remember their true identities. The record she keeps---encoded in the Book of Lost Names---becomes even more vital when her Resistance cell is betrayed and Rémy disappears.
As the Germans overrun the library where Eva and her allies have been working, she must run for her life, not knowing if she'll ever see the book again. But she has encoded in its pages one last, vital message---and she will never stop hoping for its answer.