Christopher Plummer

To raise money to buy Miss Clavel a birthday present, Madeline starts a detective school. Meanwhile, Miss Clavel is receiving mysterious gifts of great value - jewels, a painting, etc. Inspector Moreau discovers they are stolen by the infamous cat burglar Le Chat and arrives to question Miss Clavel.

The American child star Sugar Dimples becomes homesick when visiting Paris, and especially misses Halloween, which is not celebrated in France. At first Sugar Dimples does not appreciate the children's efforts to cheer her up, even when the girls and Pepito turn an abandoned castle into a haunted house.

For their entry in the Science Exhibition, Madeline and the girls create a magnificent scale model of a hot air balloon. During the exhibition, Genevieve falls asleep in the balloon's basket and the balloon inadvertently takes off. With Genevieve floating over Paris, Madeline and Pepito enlist the aid of Professor Windbag, a hot air balloon "expert" who is more full of hot air than knowledge.

Madeline convinces the young Prince of Monaco to remove his crown so he can spend an afternoon as an ordinary boy. But when the children return from the park, the priceless crown is missing. Using her superb detective skills, Madeline launches a citywide search that eventually implicates Pepito!

Madeline, the girls, Pepito, and his three naughty cousins go on a field trip to Egypt. Nicole becomes terrified when they experience a series of mishaps - from getting locked in the museum to getting caught in a desert dust storm on camelback. Then the group gets lost in the pyramids and encounters a mummy who speaks to them in an echoey voice and curses them with bad luck!

Pepito becomes frustrated when an old lamp from the Embassy attic fails to produce a Genie, and he throws the lamp in the trash. That night a frayed old Magic Carpet comes to Madeline's window and asks her help in finding the discarded lamp, because it does indeed have a Genie inside.

Madeline, Pepito and the girls take the famed Orient Express to Istanbul to compete in the International Spelling Bee. When a snake charmer on the train announces that his prize cobra is missing, Madeline and Pepito volunteer to search for the missing serpent (although the other girls refuse).

The girls and Pepito visit Pepito's relatives' hacienda in Spain and encounter Pepito's cousins who are naughty and mischievous "bad hats", the way Pepito used to be (only worse!) The cousins terrorize everything in sight: various animals, the guests at their parents' fiesta, and even the girls. But after Madeline rescues a baby bull from their reaches, the Horrible Hats meet up with "El Enojado", an angry toro who teaches them a lesson.

Lord Cucuface becomes convinced that the girls have musical talent and schedules a Bastille Day performance. But really it is only their victrola - and Chloe - who have the talent, and when Chloe is hospitalized after a pillow fight accident, the girls lose hope. Finally Madeline (with the help of Miss Clavel) motivates everyone to practice, and the concert is a success.

After being evicted from the opera for barking along with her favorite arias, Genevieve is dog napped by an impresario who sets her up at a dinner theatre. When Madeline finally catches up with her talented canine, Genevieve, now a star is reluctant to go home because she is still embarrassed about the incident at the opera. It is up to Madeline to convince Genevieve how much she is missed at the Old House.