Easter Island, isolated and mysterious, is a riddle. What happened to the Rapa Nui, who once populated this ancient Eden? They carved iconic gigantic statues – the Moai – and lived in a culture of cooperation. Then something failed. Labyrinthine cave systems yield grim clues. Now, this update to the classic National Geographic special Easter Island Underworld, scientists have discovered that another sad fate may be in the island’s future – total disappearance.