When a pilot suffers a heart attack at 35,000 feet, a commercial airliner filled with passengers crashes into a nuclear power plant in the small town of Waketa, Minnesota, which becomes ground zero for a catastrophic national crisis with global implications. The International Nuclear Event Scale tracks nuclear disasters. It has seven levels. Level 7 is a Major Accident, with only two on record: Fukushima and Chernobyl. There has never been a Level 8. Until now.