An abandoned town in the Nevada desert is the ruins of an American Atlantis, destroyed by catastrophic floods when the Hoover Dam was built; today, experts investigate the secrets of this eerie ghost town as water levels recede and the city reemerges.

A mysterious town in the hills of South Africa was once a booming community, but today, the eerie place is deserted; experts reveal the cataclysm that caused the people of this once-prosperous town to suddenly leave and never come back.