Rosamund Atherton is nervously contemplating becoming the youngest ever Head Girl of St Peters when she learns that the Head, Miss Catcheside, has been seriously injured in a train accident and will not be returning to school that term. The prefects are shaken, but after an encouraging talk from the Senior Mistress, Miss Phillips, they decide to carry on do their best with the coming term. Rosamund urges that St Peter's should beat all of its previous records in all sport, hobby and examination activities.
Rosamund has to deal with misbehaviour from the lower school with which she does successfully but it leads to bad feeling between her and her sister, Allegra but a serious outbreak of illness leads to the school closing early and the bad feeling is forgotten in the events.
When the next term begins in January several of the girls are sent away to recuperate including Con Atherton with her mother and brother Noel. The girls are cheered by a visit from the Head on the first morning.
Shortly into the term there is an outbreak of sentimental behaviour in the lower school coinciding with the arrival of a new girl but Rosamund and the prefects manage to stamp it out before too much damage is done.
Rosamund's entry into a prize essay competition is destroyed in a fire at home but she manages to resubmit an improved version and the term ends with a series of practical jokes by IIIA who are justly punished.
The third term sees the return of Miss Catcheside to the school, and the convalescing members of the Atherton family return home. There is excitement when St Peters beats The Grange at tennis for the first time in four years, especially since Rosamund, the reserve, has been called up to play. The term ends with good news for the Athertons, for Miss Catcheside and for Rosamund herself.
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