P’tit Quinquin, now become Coincoin, has grown. His love, Eve, has abandoned him for a girl, Corinne. He and his pal Fatso are still running around raising hell in their region where the inhabitants, in disguise, wander in and out of the parades put on by a nearby carnival. In a meadow, the two boys happen upon a curious magma that looks like it’s fallen from the sky. The indescribable Captain Van der Weyden, seconded by his faithful sidekick Carpentier, conducts the investigation. Meanwhile, new signs of extra-human activity pop up.