The indomitable Madeline (Hatty Jones) and her 11 friends live at a school run by Miss Clavel (Frances McDormand) in an old house in Paris. The small but adventurous Madeline falls into the Seine, only to be rescued by a dog whom the girls later adopt and name Genevieve, and matches wits with Pepito, the devilish son of the Spanish ambassador who lives next door. The future of the school is in jeopardy when Lord Covington (Nigel Hawthorne) abruptly decides to sell the house, but Madeline masterminds a plan to scare off buyers. After foiling a plan by Pepito's shifty tutor to kidnap him, Madeline and Pepito make a daring escape and return home in triumph. Finally, using her childlike clarity to see into the aching heart of Lord Covington, Madeline makes a touching, last-minute effort to save the school.