The girls of St. Trinian's are once again unsatisfied with their lot. Under the continued guidance of Flash Harry, they determine that the best route to getting their way is to form a trade union, signing up the rest of the country's girls schools and declaring a closed shop.

But St. Trinian's is, of course, not like any other girl's school, and they'll have to infiltrate each individual institution to achieve their ends. When they unknowingly kidnap a foreign Princess, divisions between the strikers begin to show, and soon they're warring amongst themselves!