La città sopra il mondo

Baron Icaro La Plume’s new plane is called the “Flying Catamaran”. Even Zagor and Chico (though reluctantly) have boarded it but, because of a storm, they have to land on a very high mountain. Ol Undas, a technologically advanced city founded by the survivors of an ancient civilization, is located on its summit. But in the city there is a power struggle: someone is using the ancient science of the people of Ol Undas to give birth to monstrous creatures! Our heroes also get involved and Zagor proves to be instrumental in defeating the evil scientist Saltur.

Zagor and Chico stumble upon a colony of descendants of Atlantis (or Mu, or a mix of both) located on the mountain. According to Martin Mystere there are 4 or 5 colonies on the mountains around the globe, one on Mount Olympus (where there is actually a laboratory of Atlantis) and one in South America ( Ol Tezuma , perhaps one Mister No came across in 1983).