Thirteen-year-old Janni struggles to feel accepted because her physical development lags behind that of the other girls her age. She feels invisible to her classmates, especially her crush Michael. When a film director conducts a casting session at school, he too mistakes Janni for a boy and chooses her to play a prince in his fairytale film.

Although Janni accepts the part, she is embarrassed about playing a boy and tells her classmates that she has been cast as a princess. The process of working on the film builds Janni's self-confidence, until she is even ready to face her classmates with the truth.