Calvin Chillcut is a storm-chaser who tracks tornadoes for the National Severe Storms Lab.  But due to the dearth of storm activity, the NSSL has just informed him to cease and desist.  Distraught over the news, Calvin ties one on and sleeps through the first twister in 2 years.  The next day, Calvin shows up at the local watering hole (the Die Hard Diner) with a hangover, and by this point, it’s clear that a major storm is headed their way.  Tess points out that Calvin doesn’t have to turn in his equipment until tomorrow and urges him to stop feeling sorry for himself and get busy.  Calvin takes her advice and starts tracking the storm and along the way stops to pick up a hitchhiker — Monica.  Calvin explains it’s his last day — barring a miracle.  And before long, that’s just what he gets — in the form of a twister.

As the Civil Defense Tornado Warning sirens sound, the Sheriff advises everyone in the diner to take cover.  Some take his advice, but most feel perfectly safe in the diner, which they believe to be storm-proof, having weathered many a storm, unharmed.  Joe, a construction foreman from Atlanta, is concerned for his wife, Laura, who’s heading to the diner with their infant daughter.  While Calvin tracks the storm and gives Monica a dose of his cynical world outlook, Tess chides the locals at the diner for blaming God for natural disasters and placing their emphasis on “luck” and superstition.  Only Joe seems to have any appreciation for Tess’ point of view.  Calvin warns Sheriff Guthrie the twister is headed toward the diner when there’s a sudden crash — Joe’s wife’s car has landed outside the diner inches from the Sheriff’s squad car — its grille impaled into the street.  With nobody in the car, Joe holds onto his faith that his wife and child are safe.  Joe heads out in search of his wife and child — along with two others (Langford T and Willard) from the diner.

Meanwhile, Monica suggests looking for Joe’s family, but Calvin is only thinking of himself, intent on saving his job.  It’s here that we get a glimpse of the source of Calvin’s pain and how a tornado struck without warning, killing both his parents, when he was a teenager.  JJ suddenly remembers something about Joe’s wife from a previous visit — that she loved antiques and that she would’ve gotten off the main highway.  Tess convinces JJ to put aside her fear and join her in the search.  Meanwhile, Monica tries to get Calvin to join in the search for the child, but he’s only thinking of himself.  Monica reveals herself as an Angel of God and explains why Calvin has failed as a storm-chaser.  That he’s allowed his rage to control his life and instead of following his heart’s desire, he turned his vocation into something it was not intended to be.

Once he’s ready to listen, he hears the cry of a child — and looks up to see Joe’s baby girl (still in the car seat) wedged between the branches of a tree.  He radios in the good news, but static obscures the message.  Langford T, Willard, Joe and Laura return to find the diner decimated by the tornado, its “luck” having finally run out.  Calvin pulls up in his truck and returns Joe and Laura’s child to two very grateful parents.