The woman with the blue star
(Book)

"1942. Sadie Gault is eighteen and living with her parents in the Kraków Ghetto during World War II. When the Nazis liquidate the ghetto, Sadie and her pregnant mother are forced to seek refuge in the perilous tunnels beneath the city. One day she sees a girl about her own age buying flowers. Ella Stepanek is an affluent Polish girl living a life of relative ease with her stepmother, who has developed close alliances with the occupying Germans. Ella begins to aid Sadie and the two become close. As the dangers of the war worsen, their lives are set on a collision course that will test them in the face of overwhelming odds." --Publisher.