Dr. Jo Harding (Helen Hunt) doesn't much care for tornadoes. As a young girl, she saw her father lost in an F5 tornado, the strongest and deadliest category imaginable. She's dedicated her life to the study of the deadly funnels and is set on testing a revolutionary tornado analytical system meant to vastly improve man's knowledge about how the storms work and, hopefully, save lives by increasing both awareness and lead time before disaster strikes. Her soon-to-be ex-husband, Bill (Bill Paxton) is serving her with final copies of their divorce papers, papers which she seems reluctant to sign. In the middle of their discussion (with Bill's new fiancé in tow), a storm hits, and Bill and Jo instantly revert to storm chaser mode, hoping to successfully unleash to the winds the above-referenced newfangled device, dubbed "Dorothy". A night of unsuccessful attempts, deadly storms, dangerous situations, and an uncooperative and nasty rival set of storm chasers just might help Bill and Jo remember what they love most, smack-dab in the middle of several of the most hellacious storms Oklahoma has ever seen.