When the school burns to the ground there's clearly been some arson around. The pupils are found guilty and the judge hands them into the care of a pretty dubious child psychiatrist. The sixth form are soon kidnapped and on their way to Arabia with the Ministry of Education, Barchester police, and an Army Bath Unit after them. But real rescue fourth form.

The fiendish girls of St. Trinian's, brought to trial at Old Bailey for burning down their school, are freed when the mysterious Professor Canford, recently arrived from the University of Baghdad, claims that he can rehabilitate them. Unaware that his benefactor, Alphonse O'Reilly, is a white slaver who plans to abduct and sell the students to an Eastern potentate seeking wives for his many sons, Canford arranges for the older students to take a cultural tour of the Greek islands. Hidden aboard the students' luxury yacht is longsuffering police Sgt. Ruby Gates, who has been ordered to relay information about the girls' activities to Superintendent Kemp-Bird, her fiancé of many years. Ruby learns that the ship is off course and wires headquarters. Before any action can be taken, however, O'Reilly sets adrift in a lifeboat Professor Canford, Ruby, and Flash Harry, the unofficial matrimonial agent of St. Trinian's. Butters and Culpepper-Brown, a team sent from the ministry of education to rescue the girls, are also put out to sea by St. Trinian's younger students, who believe that they are helping their older classmates. Although the older students are delivered to the emir's palace, they hold off his ardent sons during a free-for-all. Rescued by police and the younger students, the girls celebrate their homecoming by burning down St. Trinian's.