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.

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. Trinians are on the hunt for buried treasure after discovering headmistress Miss Fritton is related to a famous pirate.