WHERE IS ATLANTIS? Plato the greatest Greek philosopher first revealed this ancient lost civilization, but no-one believed him. It's the world's most famous mystery. WHO CAN FIND IT? Not Chris, Demi and Alex, surely. They're too young, with too many problems of their own. But they're given a mission by their Granddad: 'Follow my clues and find Atlantis. Which I never could.' He was a super-Nerd who knew Greek. But dead. Wasn't he? THE ISLAND Granddad's...