Darrell Rivers is now in the third form, and is returning to Malory Towers for the summer term. On the journey back, Darrell's father picks up a new girl from America who is living in England for a year. Darrell finds Zerelda Brass very strange and different from the other girls she knows; she seems much too grown-up for school at fifteen and has her hair made up very elaborately. Two other new girls arrive at Malory Towers in the third form. There is horse-mad Bill Robinson, whose real name is Wilhelmina, who is so attached to her fierce horse Thunder that she daydreams in lessons. There is also the conceited Mavis, who was new the term before, and never tires of telling everyone what a wonderful opera-singer she would be because of her wonderful singing voice.
From the first day of school, Zerelda has a hard time trying to keep up with the fourth form work, and her lazy mind does not help her when it comes it receiving order marks that count against the whole form. A surprise is in store for Darrell though, in the first week the games captain offers to train her for one of the reserve lacrosse teams. Zerelda then surprises the whole form with her bad acting, which she is convinced will win her the part of Juliet in the third form play. Half of the term has not passed when Bill discovers that Thunder has colic and could die, so she and Darrell and Miss Peters (the third form mistress)come to his rescue at three in the morning, leaving Bill very proud of Miss Peters. On the same night, Mavis sneaks off to a talent contest in the next town and misses the last bus back to Cornwall. She has to walk back to school, and is discovered lying on the roadside by Miss Peters. After her escapade she loses her voice and is not allowed to do any more singing for a year.
Not long after half-term, Zerelda makes a fool of herself whilst trying to audition for the part of Juliet in the form play, and soon realises that she has not got the talent to become a great actress. This lesson humbles Zerelda, and she becomes friends with another gifted failure, Mavis. At the end of term, Darrell is put into the lacrosse team and wins a match against Barchester School, which makes her very happy indeed!
The review of this Book prepared by Liza Rosette