Episode 13: Run Marie Run!
Marie wanders off from the beach camp, playing with King while the adults of the Nautilus tend to gathering supplies and relaxing after such a long stay at sea. However, she gets lost and runs into Neo Atlanteans, also anchored on the island. Her escape is facilitated by Sanson, who eventually develops an emotionally affinity to the young orphan. As the two of them come storming into camp, the mechanical beast following them smashes into the ground, and its pilot emerges with a loaded weapon.
Episode 14: The Valley of Dinicthys
Back on the Nautilus after breaking camp, Nadia and Marie contract a potentially fatal figure that can only be treated with a rare plant that grows near the bottom of the ocean. Captain Nemo along with Hanson, Sanson and Jean journey to find the healing herb but find the sea floor as treacherous as the surface.
Episode 15: The Nautilus Faces its Biggest Crisis
Ambushed again by the Garfish, the Nautilus sustains heavy damage. But when they surface for repairs, Nemo finds an entire American fleet ready to fire on his ship. Pelted with cannon fire, the Nautilus once again submerges only to find that saving the ship means sacrificing some of the crew, a circumstance that horrifies the blindly idealistic Jean and Nadia.
Episode 16: The Mystery of the Lost Continent
Having to bury fallen comrades, the Nautilus journeys to the once thriving Atlantis, where Jean and Nadia get their first taste of this strange but spectacular culture, long destroyed at the hands of its own technology. Jean also, surprisingly, discovers some of his own history there as well.