It resembles a terrifying Stephen King novel, but it's all too real. In a lakeside village in Cameroon, West Africa, 2,000 people mysteriously die in one night. Witnesses claim their neighbors were suffocated by a white fog as they slept. Without any other clues, the question remains, was this Death Fog natural or man-made? In this area of volcanic activity, could the deaths have been caused by toxic fumes? Or was something even more sinister at work? National Geographic returns to the village to collect eyewitness accounts, conduct chemical experiments, and draw controversial conclusions.