Leo must write an essay for school. His theme: the Marsupilami. He writes a lot, take pictures and interviews. So with Yamatunga, who tells him, among other things, that tomorrow is the summer solstice, the day on which he made the decision many years ago to be Yamatunga, protector of Marsupilamis. When Leo the next day visited the Marsupicoatl pyramid and the sun goes down, the temple closes suddenly. Yamatunga explained that needed to be in order for the Yamatunga apprentice can be adjusted in peace on his future life. When Leo has freed itself from the temple, his mind is made up. He will one day be Yamatunga.
Théo fait un exposé sur son meilleur ami, le Marsupilami. Yamatunga, le sorcier lui raconte comment et pourquoi on devient gardien des Marsupilamis. Théo fasciné, rêve de le devenir un jour. Il ne sait pas que le sort va lui en fournir l'occasion…
