As a powerful storm approaches, university professor Dr. Jo Harding (Helen Hunt) and an underfunded team of students prepare the prototype for DOROTHY, a groundbreaking tornado data-gathering device conceived by her soon-to-be ex-husband, Bill (Bill Paxton). When Jo tells Bill that the device is ready for testing—and that their privately funded rival Dr. Jonas Miller (Cary Elwes) has stolen the idea and built his own—Bill rejoins the team for one last mission. In a race against time, the estranged couple finds themselves in the crosshairs of one of the most violent and powerful storms ever recorded.