The Twins at St. Clare's is the first novel in Enid Blyton's school series set at the fictional boarding school, St. Clare's. The story introduces the wild and spirited twin sisters, Pat and Isabel O'Sullivan, as they arrive for their first term. Initially resentful of being sent away, the twins struggle to conform to the school's rules and frequently clash with the mistresses and other girls. The book details their experiences making new friends, facing challenges, and ultimately beginning to realize that the school offers more fun and friendship than they first imagined.