Moon Jules Verne and professor Artemius's team attend the festive launch of an American cannon launch to the mean. Despite the protection of a US secret agent's team, the cannon is suddenly broken loose by a tremor and dragged underground. The gang pursues it, and finds they're chasing a contraption manned by Nemo and some of his crewman, who drag it to his submarine Nautilus. During the dangerous expedition, Artemeius explains how ambitious Nemo, now identified, already was when they were brilliant university roommates.