In AD 536, a volcanic eruption meant our planet was enveloped by a cloak of lethal dust which changed the climate for decades. The sun's rays grew dim and total darkness reigned for days. It was a catastrophe of unparalleled proportions. Tens of millions of people died around the globe as a bubonic plague epidemic broke out. But in a way it was only the beginning of the crisis. The waves of migration and the military, political and religious changes which the disaster set in motion re-ordered society throughout the world: the collapse of the Roman Empire, the invasion of the barbarian hordes and the rise of apocalypse-inspired Islam. It was the nearest humankind has ever come to Doomsday and it marked the real beginning of the modern era. The author sets the record straight by placing the pivotal point in world history as the mid-6th-century Dark Ages and shows how our fragile civilization almost ended.