The genetic diversity of the entire human race is startlingly narrow, suggesting that at some point in our distant past, our ancestors were nearly wiped from the face of the Earth. The culprit was not disease or war, but an apocalyptic geological event that plunged the globe into a devastating, decades-long freeze. Around 74,000 years ago, the Toba supervolcano in present-day Indonesia detonated in the largest eruption of the past two million years. The resulting ash cloud obliterated the sun, triggering a sudden, brutal volcanic winter that decimated global flora and fauna and reportedly reduced the global human population to a mere few thousand breeding pairs. This gripping archaeological and genetic investigation reconstructs the timeline of the Toba catastrophe. It explores how our resourceful ancestors survived the sudden collapse of their ecosystems, how the resulting isolation forced rapid evolutionary leaps in cooperation and tool-making, and how this terrifying bottleneck permanently scarred human DNA. Witness the greatest survival story in the history of our species. Understand the delicate balance of the Earth's climate systems, and discover how a single mountain in Sumatra nearly ended the human experiment before it truly began.