DESCRIPTION: The Virunga Mountains in East Africa are home to two of the world's most dangerous, spectacular, and least understood volcanoes. In this two-part NOVA special, an intrepid team of volcano experts leads a daring expedition to reach their high-altitude craters, one of them filled with a fiery lava lake that bubbles and churns at over 1,000° F. The team deploys innovative imaging and sampling tools to seek clues to the hidden volcanic forces that are splitting East Africa apart, and to predict the next devastating eruption that could threaten millions who live in the shadow of these monsters.