After one term as Head Girl, Bette Rincini has left the Chalet School and wild child Grizel Cochrane, almost eighteen, is to take over, although she is nearly demoted before she begins. Madge is now Madge Russell and her partner Mademoiselle LaPattre has become Headmistress. Joey and the Robin have spent Christmas in the New Forest at Miss Maynard's family home and Grizel travels back to Austria via Switzerland for the new term with them.
Despite a shaky start, Grizel is to become an exemplary Head Girl. In her very first Prefects meeting she is called on to handle a difficult confrontation with one of the Prefects, the results of which will make the Easter term very difficult for her. Returning from a visit home, Marie von Eschenau reveals that she has found out about some caves near the school, although not where the entrance to them lies. The story interests Joey greatly.
At half-term Grizel accompanies Jo and Robin up to the Sonnalpe to spend the holiday at "Die Blumen", the Russells home. During this half-term break Madge makes her famous comments about death to Grizel and Joey, something which will later sustain them.
In the second half of the term the Robin gets lost and Grizel and Jo set off to find her. She is abducted but un-harmed by a mad old man, Herr Arnolfi, from whom the trio (with the faithful Rufus) have a dramatic escape. They later realise that they must have been very close to the entrance of the caves that Marie spoke of.
The Summer Term is marked by dramatic news from the Sonnalpe and by the arrival of new girl Cornelia Flower, a 14 year-old American. Cornelia does not make a good start at the school as she is a rather impudent prankster, and considered a liar and a cheat by the other girls.
Unfortunately, while sent to bed for her sins, Cornelia overhears this opinion being aired and vows to get back at everyone. Further idle talk about the mysterious caves and their possible whereabouts sets in motion Cornelia's plan as she sets off alone to try and find them. When she is discovered missing, it is Jo who guesses her destination and hares off with Grizel and Friedel von Gluck (with whom they had been picnicking with some old girls) to find her. All ends well and Cornelia begins to settle down having learnt her lesson.
The term comes to an end and Grizel leaves the Chalet School bound for music study in Florence to the sound of three cheers.
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