The children's story starts with the twins Pat and Isabel O'Sullivan looking forward to enjoying their first summer term at St. Clare's.

As a result, Pam is initially disliked by all of the girls except Carlotta and Isabel, who take pity on her when they realise that she is afraid to tackle Prudence as she does not want to be on her own.

Encouraged by the two older girls, Pam eventually stands up to Prudence and ends their forced friendship, becoming friends with Carlotta instead.

Bobby initially doesn't seem to care for anything or anyone until Miss Theobald tells her that she is cheating her parents badly.

During the term, while Prudence is spying on Carlotta, Sadie is kidnapped, and Carlotta - who finds her tied up, gagged and blindfolded in the back seat of a motor car - goes after her, and stages a fake road accident, during which she manages to rescue her with the help of her circus' friends.

The term ends happily for most, with Prudence leaving because everyone hates her for her part in Sadie's kidnap (she could have alerted Sadie to the fact that she was in danger when she and Pam met a strange man lurking around the school entrance but was too busy trying to get Carlotta into trouble to realise this, and ignored Pam's warning to report the man to Miss Theobald), Sadie herself bouncing back strongly from her kidnapping ordeal and preparing to go back to America, and the other girls looking forward to going into second year except Prudence, who is leaving and Pam, who is too young to move into the second form.