The little horrors of St. Trinian's hatch yet another fiendish plot - a trade union for British schoolgirls. Their friend and mentor, Flash Harry, suggests a plan which involves kidnapping girls from other more respectable colleges and substituting their own "agents." Thus begins a hilarious, often bloody, battle of wits as the girls meet resistance not only from Olga Bandameer, their Headmistress, but from the Ministry of Education, a private detective and an oil sheikh. Despite all his desperate efforts to foil the conspiracy, the Minister has to face a growing realization that the girls' demands will have to be met - for him this will mean a very great and very personal sacrifice.