Academy Award winner Helen Hunt stars as Dr. Jo Thornton-Harding, who as a small girl watched her father sucked to his death from her family's storm cellar by a massive tornado. Now a storm chaser, a scientist who risks her life to study the dark side of nature by taking her data-transmitting instruments directly into the path of a deadly storm, Jo chases the largest tornado to ever strike Oklahoma as her marriage implodes and rival scientists will stop at nothing to steal her breakthrough.