When a terrifying new PE teacher, Mr Biggspitt, insists he's going to prepare the students for school sports day, Sabrina and her friends are not really bothered. But a distracted Sabrina accidentally wins the running trial and Mr Biggspitt is convinced that he has a star in the making.

This is a real problem for a secret princess still trying to hide her identity. To make things worse, Mr Biggspitt picks Sabrina and Liam for the elite team, but not her other friends, Charlie and Awful Agatha. Meanwhile, Uncle Ernie reveals a family tragedy that breaks her trust. Why does everyone in her life seem to be betraying her?

Feeling lost and confused, Sabrina turns to Mr Biggspitt for help, which leaves her with an impossible choice. She has the skills to win the school sports day, but does she want to lose her friends along the way?