Miss Grayling reveals disheartening news. In one last attempt to save the school, Darrell and Sally try to find Lady Jane’s lost treasure. Gwen’s secrets come to light.
A teacher and Gwen are quarantined after finding out they have the measles. Darrell finds out disturbing news about the future of Malory Towers. Sally takes on extra responsibilities.
Ellen is stressed that she’ll lose her scholarship and stays up all night studying for an exam. Gwen gets her hands on Darrell’s diary and discovers Darrell's secret.
In an attempt to impress her parents, Gwen auditions for the lead role in the upcoming school play. Darrell and Sally devise a plan to save the school.
Alicia convinces Darrell to help her play a prank on their teachers with invisible chalk. Meanwhile, Mr. Parker becomes stricter with his teaching. Mary-Lou finds her voice and stands up for herself.
Darrell and her class return to Malory Towers. The first order of business: elect a new class leader. Gwen decides to take the new girl under her wing and become her best friend.