So the big reveal of the first minutes is that Estabans forefathers is from Atlantis, which Tao overhears, establishing a couple of episodes of antagonism between the main characters. Which feels rather forced. IT'S OVER 10 000 YEARS!!! JESUS! Did his parents brainwash him into hating atlantiens that was belived destroyed at the same time? That's plausible I guess, but he has known Estaban for months, he saved him from the Olmecs and so forth, why should it matter? And really, both civilizations destroyed each other in a cold war turned nuclear as said by the High-Priest of the city of Gold aka Estabans father... oh, alright, maybe Tao has legimitate concerns in disbeliveing it, but it still feels forced on screen.
Anyway, Ambrosius brings forward the Mu pyramid which they blast with the dragon statue revealing semi-holographic shapes were one seems like a encycopedia with blue-prints, symbols and text in Mu. One symbol they identify as a carving in the gobian desert so after taking the old man to his home they head west to an oasis. There they refill their rations and promis to guard a merchants wares so they can stay. Meanwhile the fued gets worse between Tao and Estaban until the night after a swim... where I guess we get a throwback to one of the Manchu Pichu-episodes of the first season where Tao and Estaban bathed in the nude, but this time with Zia (of course completely covered by the water). She fakes a Jaws-moment to get the boys to save her and stop feuding each other. Doesn't help and after an interlude by a camel Tao accidently scares it and Estaban gets lost in the desert. Tao and Zia gets to him, a sandstorm breaks out and the fued reach it's climax and Tao disapears in the storm.
I can see how it on papers seems like an epic downpoint in the story, the kids seeing a split based on their forefathes who caused the destruction of the greatest civilizations on earth. Sadly it feels a bit rushed with just that fact caussing it. Maybe it also linked toward Tao's inferiority complex toward the other kids since in the lastest episodes he wasn't of much use since he isn't one of the chosen and doesn't have a medalion, he also almost caused their death. Still, lashing out on a close friend, also the only friends he have had is a bit hard to take just at face-value. Maybe with flashback from his parents or the story of the evil atlanteans to make us symphatize, at the moment it just feels out of nowhere and stubborness from his side.