The scene was 74,000 years ago, on the island of Sumatra. A volcanic eruption triggered the sudden and violent collapse of a vast regional plateau. Toba, as the volcano is known today, was the largest volcanic eruption in the last 25 million years. But Earth has seen far larger. 250 million years ago, an eruption in what's now Siberia lasted a million years and was probably responsible for the greatest episode of mass extinction in Earth's history. The award-winning Supervolcanoes looks back at rare classes of eruptions that have marshaled the energy that lurks, like a sleeping dragon, beneath the surface of planet Earth. The program moves beyond Earth to explore the impact of giant volcanic eruptions around our solar system. On a visit to a legendary North American hot spot, Yellowstone National Park, the film asks: can a supervolcano erupt in our time? Narrated by Benedict Cumberbatch.