10-year-old Kathy Montag moves to a big city in Brandenburg. Before that, she lived in the Harz Mountains together with her father Peter. Her mother has died a few years ago. The girl finds her new home very exciting, and since Kathy takes an interest in everything she encounters, she keeps finding herself in peculiar situations such as a brigade party or the shooting of a historical epic movie. Her classmates consider her an oddball and even her father is unhappy about his daughter′s development.