Leaving a notorious trail of arson behind them, the St. Trinian's schoolgirls are always on the move. Their headmistress is more than 'just friends' with the Minister of Schools. Armed with a government grant, she re-houses her girls in yet another home - Hamingwell Grange. What she doesn't know is that the Great Train Robbers have got there before her. And left £2.5 million hidden under the ballroom stage....