When their beloved school is threatened with closure should the powers that be fail to raise the proper funds, the girls scheme to steal a priceless painting and use the profits to pull St. Trinian's out of the red.
The girls of St. Trinians are on the hunt for buried treasure after discovering headmistress Miss Fritton is related to a famous pirate.
Story of manic schoolgirls who are more interested in racing form than books as they try to get-rich-quick, aided by the head-mistress' brother, played by Alastair Sim, who also plays the head-mistress.
The girls of St. Trinian's decide they are being asked to do too much work so they go on strike.
St. Trinian's contrives to win a competition which has a European trip as the prize, in order for the Girls of the Flash Harry St Trinian's Marriage Bureau to meet a rich Roman royal.
A dubious child psychiatrist is put in charge of the St. Trinian's school after it burns down. The sixth form are sent to Arabia to become harem girls. The Ministry of Education, Police and army go to rescue them, but it is the notorious St. Trinian's forth form who are going to make the real difference.
The all-girl school foil an attempt by train robbers to recover two and a half million pounds hidden in their school.