Li'l Quinquin has grown up and now goes by the name of Coincoin. His girlfriend, Ève, has left him for another girl, Corinne, but he continues to run wild with his friend, Fatso. One day, in a field, he discovers a strange black magma that seems to have fallen from the sky. As Inspector Van der Weyden and his loyal assistant Carpentier investigate, new "extra-human" events occur.

Confronted with the irrational, Van der Weyden and Carpentier try to understand: are they seeing signs of alien activity? The invasion already seems to have begun. And as Coincoin seeks solace in the arms of the pretty Jenny, the locals give birth to clones as emotionless as they are disturbing.

As more and more doubles appear and confusion grows, everyone seems to agree on one point: the end of the world is nigh. As for Van der Weyden and Carpentier, they continue to rush hither and thither and back again without getting closer to understanding anything at all.