Six-hundred-thousand years ago the largest volcano in the Western Hemisphere erupted; covering much of what is now the Central United States in a thick layer of ash. The cataclysm left behind a massive caldera that today is known as Yellowstone National Park and it’s about to happen again. After a meeting with the President, Milton Bainbridge, a Yellowstone volcanologist is found dead under mysterious circumstances. USGS volcanologist, Jason Trask, is called in from overseas as a replacement, much to the disappointment of Bainbridge’s assistant Carlene Carlson, who was hoping to be promoted. Trask and Carlson discover records, left behind by Bainbridge, that indicate the super volcano is about to erupt again, only this time the survival of millions of Americans, in thirteen states, are threatened if they cannot be evacuated from the deadly path of the fallout. To make matters worse, a terrorist organization is planning on using the disarray in the aftermath of a Yellowstone eruption to topple the government of the United States. Trask and Carlson face off against a government that doesn't believe an eruption is eminent and a terrorist organization preparing to use that denial to their advantage. Caldera is a thrilling peek into the lives of the volcanologists assigned to Yellowstone National Park and the challenges they face when presented with the reality of a national disaster of unimaginable proportions.