Beneath Yellowstone's geysers sits a magma chamber some 50 miles across, and this Spark documentary asks what happens if it erupts the way it has three times before. Volcanologists and geologists lay out the scale involved, an event potentially a thousand times more powerful than the 1980 Mount St. Helens blast, and trace how ash, pyroclastic flow, and climate disruption would radiate outward from Wyoming across the continent. Computer modeling and simulated eruption footage stand in for the real thing, showing likely ashfall zones stretching into the Midwest and beyond, while interviewees walk through the monitoring systems currently tracking the caldera's seismic activity and ground swelling. The film weighs the geological evidence for how much warning an eruption would actually give against worst-case scenarios of collapsed infrastructure and agricultural failure. It stays grounded in what park scientists currently observe rather than pure disaster speculation, framing Yellowstone less as an imminent threat than as a natural system whose full destructive range is still being measured.