Gargoyle takes Nadia before the puppet leader of Neo-Atlantis, Emperor Neo, who reveals that he has a strong connection with both Nadia and Nemo. Eight time zones away, Nemo and the others plan to fight Gargoyle in a final duel. Throughout, both Jean and Nadia learn about the origins of the Atlanteans.
Gargoyle's battleships appear over Tartessos. To save Jean and the others, Nadia surrenders herself... but not before Jean swears to save her. Forced to flee from Gargoyle's battleships, our pals run into Captain Nemo and his crew, who have survived... and now operate a superpowerful battleship called the New Nautilus.
Trapped inside a mysterious chamber, Nadia learns from a disembodied voice that their island home is actually a space satellite, Red Noah--and that she is the heir to the throne of Atlantis as well as not human! Tremors engulf the island as Grandis and the others prepare to set off, but Jean returns to save Nadia.
Four months afterward, the Gratan is nearly repaired, and soon our pals will set off for Africa. But first Jean and Nadia go off on a hike which leads them to a mysterious underground cavern that turns out to be more than they suspected. The exploration culminates when Nadia falls into a trance and vanishes behind a wall, leaving her clothes in Jean's arms! During all this, Ayerton tries to make his move on Grandis.
As a result of Nadia's foolishness, the children only have meat for food. This infuriates Nadia so much that she declares to starve... until she becomes desperate to eat a can of rotten spinach, getting sick. Jean sets off to find a cure, only to become intoxicated by hallucinogetic mushrooms(!). Overwhelmingly grateful, and stupidly unaware that Jean is not himself, she gives him his first real kiss....
After relocating Jean, Nadia, Marie, and King to his personal quarters (which he will later jettison from the doomed Nautilus), Nemo finds Electra holding a gun on him. In an extended flashback sequence, Electra reveals her tormented past, her complicated feelings for the captain... and a horrifying connection between Nadia and Nemo.
Jean's latest invention goes disastrously wrong and accidentally alerts the Garfish to attention. Nadia's detestation of Nemo and jealousy of Jean's friendship with Electra dangerously intensifies--until she finally learns that the Nautilus is merely fighting to destroy Gargoyle and that Electra poses no threat to Nadia's relationship with Jean. During all this, Gargoyle is informed of the Nautilus's prescence and devises to set yet another deadly trap....
Jean is tired of being treated like a child by the Nautilus crew. Hoping to cheer him up, Nadia suggests Jean to build another aircraft. Inspired, he sets off to do just that. At first he is determined to construct the new helicopter by himself, but then realizes he still needs the support of some grown-ups. With Hanson's help, Jean completes the craft and takes Nadia on a very delightful test flight. While airborne, Jean promises that he will one day take Nadia to Africa....
Captain Nemo's vessel falls into yet another deadly trap set by Gargoyle--one which involves the Garfish and a surprise attack from American battleships. The subsequent damage costs the lives of several sailors--including a friendly young engineer named Ensign Fait. Jean, who had become friends with Fait, is horrified and devastated to witness someone being killed by the technology he had so strongly idealized with.
Nemo and Electra appoint Jean, Nadia, and the others to new positions on the Nautilus. Jean is permitted access to Electra's library of books so that he can learn how to use the knowledge for mankind's benefit; simultaneously, he, Sanson, and Hanson are given a tour of the Nautilus. Marie and King, meanwhile, are reduced to schooling from Electra, much to their dismay. Grandis and Nadia are assigned to cook in the kitchen. An intense rivalry is ignited between Electra and Grandis as they compete over Nemo's love. Finally, Jean discovers the source of the Nautilus's power, and is quite disturbed when Nemo tells him that the vessel is a killing machine....
Jean, Nadia, Marie, and King are taken aboard the Nautilus with their new enemies-turned allies, Grandis, Sanson, and Hanson. Technophiles Jean and Hanson are thrilled to be aboard the Nautilus. Grandis becomes dangerously smitten with Captain Nemo, much to Sanson's consternation. Nadia, meanwhile, is very suspicious about the submarine and its crew, particularly Nemo, who reacts with surprise upon seeing her for the first time....
Imprisoned by the wicked Gargoyle, Nadia is forced to admit that she gave her Blue Water to Jean before turning herself in (to save Marie and King from a horrible fate). As the search for Jean is on, the boy desperately tries to find her. Simultaneously, Grandis, Sanson, and Hanson, who have also been imprisoned by the soldiers, break out of their prison cell and attempt to escape. While Gargoyle tours Nadia around his base, he showcases Neo-Atlantis's secret weapon, a tower known as Babel with the power to obliterate an entire island!
Jean, Nadia, and King are rescued by another vessel--an impressive and mysterious submarine known as the Nautilus (and yes, the captain's name is Nemo). Here, they learn from Nemo's pretty first officer, a young woman named Electra, that the vessel is in pursuit of a sinister enemy. After an unsuccessful attack against the deadly submarine Garfish, the Nautilus repairs Jean's sea plane, and the children take off for another adventure.
With Grandis and her two accomplices, Sanson and Hanson, in pursuit, Jean takes Nadia back to his home in LeHarve. His grumpy aunt refuses to take Nadia in, but Jean lets Nadia stay at his own house. The following day, Jean and Nadia set off for Africa in one of his aeroplanes. They do not get far, however, when Jean's invention fails and falls into the sea....
Jean, a 14-year-old orphan, sailing into Paris to help his uncle design an airplane for the Paris Exposition's flight competition meets a pretty young girl named Nadia and her pet lion cub, King. He ends up rescuing her from a woman named Grandis who is trying to get Nadia's jewel, the Blue Water. Nadia leaves the only home she ever knew - a circus - as Jean has offered to help her search for her place of origin, starting with the random choice of Africa...