In 1943 Hamburg, Sophie Bergmann, a Jewish teenager, finds solace and strength through swing dancing in the underground clubs of Nazi Germany. But one night, a raid led by fanatical Hitler Youth member Klaus Schmidt, shatters that refuge, forcing Sophie and her friends to flee. Just as they brace for capture, a strange, blinding light overtakes them, and they vanish from their own time.

When Sophie regains consciousness, she’s surrounded by the unfamiliar sights and sounds of modern-day Milwaukee. With her are four other teens from the club: Ruth, her best friend and fellow swing dancer; Maria, a quiet but defiant artist; Hans, who wrestles with his reluctant role in the Nazi Youth; and Klaus, who remains as fervent as ever in his radical beliefs. For Sophie, the disorientation is compounded by glimpses of a painful history that, in this new timeline, has already unfolded.