ONE KNOCK AT THE DOOR, AND STEFANIA HAS A CHOICE TO MAKE.. It is 1943, and for four years, sixteen-year-old Stefania has been working for the Diamant family in their grocery store in Premysl, Poland, singing her way into their lives and hearts. She has even made a promise to one of their sons, Izio—a betrothal they must keep secret since Stefania is Catholic and the Diamants are Jewish. But everything changes when the German Army invades Przemysl. The Diamants are forced into the ghetto, and Stefania is alone in an occupied city, the only person left to care for Helena, her six-year-old sister. And then comes the knock at the door. Izio's brother Max has jumped from a train headed to a concentration camp. Stefania and Helena make the extraordinary decision to hide Max, and eventually twelve more Jews, too. Then they must wait, every day, for the next knock at the door, the one that will mean death. When the knock finally comes, it is two SS officers, requisitioning Stefania's house for the German Army. With two Nazis living below, thirteen Jews hidden above, and a little sister by her side, Stefania has one more excruciating choice to make.