Audrey, Solange, Val, Celia and Winifred (usually called Win) are schoolgirls staying on the Platz to be near sick relatives. Bored, and trying to entertain themselves, they decide to build a Campfire. Unfortunately, they do it within the grounds of the Chalet School, and are scolded by Miss Dene.

After this, and an encounter with Len Maynard, the group declares war on the Chalet School. Their tricks try the patience of staff and students alike.

The girls play a variety of tricks on the Chalet School including blocking the path during a school walk, throwing stinkbombs at the prefects and spreading pepper on the food in the Speisesaal.

Over time, the girls come into contact with pupils, ex-pupils and school events. This helps change their attitude towards the Chalet School. And when Win goes missing, it's the Chalet School that saves the day.

Meanwhile, the Fifth Form sits GCE exams, and an ex-Chalet schoolgirl faces an uncertain future.