Three and a half thousand years ago, the tiny Aegean island of Thera was devastated by one of the worst natural disasters since the Ice Age - a huge volcanic eruption. This cataclysm happened 100km from the island of Crete, the home of the thriving Minoan civilisation. Fifty years after the eruption, that civilisation was in ruins. Did the volcano deliver a death blow to the Minoans? It's a whodunnit that has haunted historians and scientists for decades.