When 12-year-old Karli moves to an old hotel in the Alps, he discovers an elevator that harbours a secret – it’s a magical time portal that transports him back to 1938! There, he befriends Hannah, a spirited Jewish girl, and Georg, a shoeshine boy. But when Georg is falsely accused of stealing, the children must solve a mystery case hidden within the hotel’s walls, all while the shadow of Nazi Germany begins to grow around them.