Germany, 1945. The soldiers who liberated the Gross-Rosen concentration camp said the war was over, but nothing feels over to eighteen-year-old Zofia Lederman.Her body has barely begun to heal; her mind feels broken. And her life is completely shattered: Three years ago, she and her younger brother, Abek, were the only members of their family to be sent to the right, away from the gas chambers of Auschwitz-Birkenau.Everyone else--her parents, her grandmother, radiant Aunt Maja--they went left. Zofia's last words to her brother were a promise: Abek to Zofia, A to Z.When I find you again, we will fill our alphabet. Now her journey to fulfill that vow takes her through Poland and Germany, and into a displaced persons camp where everyone she meets is trying to piece together a future from a painful past: Miriam, desperately searching for the twin she was separated from after they survived medical experimentation.Breine, a former heiress, who now longs only for a simple wedding with her new fiance. And Josef, who guards his past behind a wall of secrets, and is beautiful and strange and magnetic all at once. But the deeper Zofia digs, the more impossible her search seems.How can she find one boy in a sea of the missing? In the rubble of a broken continent, Zofia must delve into a mystery whose answers could break her--or help her rebuild her world.