Max-Ernest points out a magazine with a picture of the Skelton Sisters on the cover, the teen pop stars who were known by the two collaborators as being members of the Midnight Sun.

Knowing this, the kids become suspicious of what they are doing, and discover that they are with Ms. Mauvais, the French woman who is one of the most evil leaders of the Midnight Sun, and that they have established headquarters in the country Côte d'Ivoire in Africa, where they take care of orphans and work on a chocolate plantation.

Later, Cass and her mother, Melanie, or "Mel" for short, sign up for a cooking class run by the famous blind chef, Señor Hugo.

At the restaurant, the kids and Mel discover that it is extremely dark to the point where no one can see anything, since Hugo wants the diners' other senses, especially taste, to be heightened during their meal.

While searching, Cass finds the box in which she was dropped off by Mr. Wallace, and then sees on a television that the kids' principal, Mrs. Johnson, is in possession of the Tuning Fork.

After taking a train to the park, the kids camp out there (with the trio nearly eaten by a lion) and later journey through the rainforest, locating the plantation with the help of a Capuchin monkey.

Hiding in the cacao trees on the plantation, the kids witness Ms. Mauvais herself talking to an elderly man, Itamar, who made a brief appearance in the first book, and dies a few days later.

Since Yo-Yoji fell into a trance that has him believing he is an ancient Samurai warrior, Max-Ernest was able to control him and command him to rescue Cass, her mother, and Simone.