Bertha Fytte is a serious and strict schoolmistress, and not well liked by the schoolgirls. Her sister Cicely runs a nearby circus, more or less successfully, and Bertha heartily disapproves. But spinster Bertha suddenly elopes, and Cicely is induced to take her place … only for one day. Cicely scrapes by teaching advanced geometry and finds an ally in van Gaard, the romantic American music teacher, who discloses to her that his qualifications are not 100% genuine. The school headmistress is retiring and Bertha is on the short list to get her job. Will Cicely try to succeed for her sister, and if she tries can she put on a good enough show to pull it off?