St Trinnain's school for spies

Sandra Gray is a spie in an all girls school. after a soccer match the school they veresed is forced to stay at St Trinnians until the flash flood has gone and the roads are clear. but Sandra is running from her past but her past is following her. as she and the rest of the girls try to hide their secret from the St John's girls something happenes and suddnely no one can leave the grounds