Even though she outperforms the competition, Genevieve is disqualified from a dog show because she is not a purebred. But after she rescues the Mayor's dog, the judges change their tune.

The girls are looking forward to a big costume bash at Pepito's house, but a week or so before the festivities they all come down with chicken pox and are quarantined in the Old House.

The girls and Pepito visit Pepito's relatives' hacienda in Spain and encounter Pepito's cousins, who are naughty and mischievous.

When Madeline's sinuses act up, Dr. Cohn suggests she go someplace warm, so Lord Cucuface sends the girls to Cannes. Not heeding Miss Clavel's warning, Madeline stays on the beach all day, and gets sunburned, so she's forced to stay inside. She is so lonely and bored, Lord Cucuface asks his director friends to bring their latest movies - and, on Madeline's suggestion, a contest - The Cannes Film Festival is born.

When Yvette is asked to pose for a famous contemporary artist, she brags to the other girls and acts superior because this obviously means she is beautiful. She gets her comeuppance when the painting is finished; it has an eye in a corner, a green face and no chin - a cubist nightmare.

While touring Versailles with Miss Clavel and the girls, Pepito disobeys a "Do Not Touch" sign, and leaves fingerprints of mud and chocolate on a priceless harpsichord. Pepito feels more and more guilty until Madeline finally convinces him to fess up and face the consequences.

When the pipes burst and the old house is closed for a plumbing overhaul, Madeline and the girls move into Lord Cucuface's lavish suite at the Ritz. While there, they help a lonely rich girl and a hungry homeless girl, and soon discover that they'd rather have each other's love than live an empty upscale existence.

Madeline and the girls help to reform an unhappy puppeteer in the Jardin de Luxembourg, who, because he never had the talent to be an opera singer, puts on marionette shows that twist the plots of classic fairy tales and disappoint children in the audience.

When Madeline gets a pair of new ice skates for her birthday, she becomes so obsessed with practicing her skating that she neglects all her other responsibilities and friendships, and finally finds that ice skating has become a chore rather than a fun hobby.

When Madeline and the girls go to Dr. Cohn for a physical, all the girls have grown several inches except Madeline, who has a dream that she will be Tom Thumb-sized for her whole life. In the end, she feels better when she discovers that Georgette, the tallest girl, has size issues as well.

After Pepito burps at the dinner table, his parents insist on sending him to etiquette school, where he is joined by Madeline and the girls. After they graduate, Pepito's unruly cousin Pablito tries to convince Pepito that manners are uncool, but Madeline helps Pepito see the light just in time for him to put on his best behavior during an event for the soccer star Pepe Pelota.

After Madeline performs a successful science experiment dropping an egg off the balcony of the old house without breaking it, Pepito dares her to drop her egg off the top of the Eiffel Tower, and the two end up getting stuck in an elevator there, and being forced spending the night.

The girls are planning a spring tea in honor of Lord Cucuface and the trustees when Sugar Dimples, the child movie star, drops in to visit and takes over, turning their simple party into a major "Hollywood" production, with over-the-top results. It is up to Madeline to bring the party down to earth and remind Sugar Dimples that it is the company that counts, not the lavishness.