Nantes (France), spring of 1840. The eleven-year-old Jules Verne, explorer and inventor, is very happy. Finally, good news for progress and knowledge in his city. Great teachers and scientists arrive for a scientific conference, while a new railway line will soon connect Nantes with Paris. However, a terrible criminal organization cannot accept this development. Thus, it plans to kidnap the scientists in order to use their knowledge for its own evil purposes.

Will the four friends manage to uncover the organization's plans? A new adventure begins for the Adventure Hunters Club of the 21st century, and Jules and his gang will need to explore a cave deep within the earth...