The O'Sullivan twins, Hanni and Nanni, have already been at St. Clare for a week. At the moment they are in big trouble with their French teacher, Mademoiselle. They have failed an essay and have to write it again as punishment. But as they want to go to the movies with the others in the afternoon, they have to sit down at night and write while the others are asleep. When they hand in their essay to Mademoiselle, the principal, Miss Theobald, is also sitting there. It turns out that the twins went to the movies instead of writing their punishment paper. However, the principal is lenient and arranges for Hanni and Nanni to have extra lessons with Mademoiselle. Suddenly French isn't so bad after all.