Increasingly wary of her father's genetic research, Rachel Kramer has determined that this trip with him to Germany in 1939 will be her last. But a cryptic letter from an estranged friend, begging Rachel for help, changes everything. Married to SS officer Gerhardt Schlick, Kristine sees the dark tides turning and fears her husband views their daughter, Amelie, deaf since birth, as a blight on his Aryan bloodline. When Rachel uncovers shocking secrets about her own history, she turns to American journalist Jason Young, who connects her to the resistance and to controversial theologian Dietrich Bonhoeffer.