Dark Age Volcano examines a massive 6th-century volcanic eruption in El Salvador, and its devastating impact on the Maya people living within its range and beyond. The program follows Dr. Robert Dull as he tries to prove his theory that this eruption is behind a worldwide climate change event that occurred in 536 AD. Across the globe, the Roman Empire was experiencing an equally devastating event in the sixth century-the onset of bubonic plague, which eventually brought the Empire to its knees.

In 1755, a powerful earthquake shakes the city of Lisbon for an astonishing 5-6 minutes. Survivors climb out of the rubble and flee to the riverbank only to be engulfed by a massive tsunami. Then the fires start. The city burns for eight days. Tens of thousands die and Portugal is crippled as an imperial power; but out of the rubble new ideas and scientific study take route. Helping to usher in a new age, The Enlightenment.

9 A.D. Three Roman Legions are ambushed and wiped out in a remote German forest during a thunderstorm. The severed head of Roman General Varus is sent back to Rome in a box and the Roman attempt to bring Germania into the Empire is stopped dead in its tracks. The battle helps create the boundary between Latin and Germanic Europe that exists to this day.

Two gargantuan armies collide on battlefields west of Moscow in 1941. Calling the shots are two dictators. For the Nazis: Adolf Hitler. For the Soviets: Joseph Stalin. Both men ignore the advice of generals and insist on victory at any cost. Caught in the middle: an astonishing seven million soldiers. It is the largest battle in human history and perhaps the most consequential. By mid-October the Soviets are on the verge of collapse, but when "General Mud" and "General Cold" arrive a few weeks later, the Nazi advance is stopped dead in its tracks.

In 1900, the island city of Galveston, Texas is on the verge of greatness. Nicknamed the New York of the South it boasts the second most millionaires per capita of any city in the nation. Then everything changes. On September 8th a massive category 4 hurricane makes landfall. Warnings about the approaching storm have been ignored. When the only bridge to the mainland is wiped out, the city's 37,000 inhabitants are trapped. The next morning, 8,000 - 10,000 are dead. It remains the deadliest natural disaster to ever strike the United States.

September 1, 1923. A 7.9 magnitude earthquake strikes off the coast of Japan. The shockwaves devastate Tokyo, Yokohama and surrounding areas. In the rubble, thousands of fires break out and are quickly whipped into a firestorm, aided by strong winds from a typhoon lurking offshore. In a downtown open space where earthquake survivors had taken refuge, the firestorm triggers an extremely rare "dragon twist" - a tornado filled with burning debris - which kills an astounding 35,000-40,000 people in just 15 minutes. Known as the Great Kanto Earthquake, this disaster remains the deadliest in Japanese history, killing between 120,000 to 140,000 people. In the political and social chaos that follows, Japan is set on a new militaristic path towards the Second World War.