On an Alabama beach, 10-year-olds Jake Perry and Melanie Smooter inspect the result of lightning striking sand. Jake asserts that they will be married one day.
In the present day, Melanie is a successful New York fashion designer who has adopted the surname "Carmichael" to hide her poor Southern roots. After wealthy Andrew Hennings proposes, Melanie returns to Alabama to announce her engagement to her parents and finalize a divorce from her estranged husband, Jake. Meanwhile, Kate Hennings, Andrew's mother and the Mayor of New York City, doubts Melanie's suitability to wed her son, whom she is grooming to run for President of the United States.
Melanie visits Jake, who has avoided signing the divorce papers. After Jake orders Melanie out of his house, Melanie empties Jake's checking account, hoping to spur him into ending the marriage. Jake finally relents and agrees to the divorce and promises to return the signed papers the next morning. Later, at a local bar, Melanie gets drunk, insults her old school friends, and outs her old childhood friend, Bobby Ray Bailey. The next morning, Melanie finds the signed document on her bed.
Melanie goes to the Carmichael plantation and apologizes to Bobby Ray. She is cornered there by Kate's assistant, sent there to gather information on Melanie's background. Bobby Ray backs up her pretense that she is a relative and the family mansion is her childhood home. Melanie reconciles with her friends and learns that after she split with Jake, he had followed her to New York to win her back. Intimidated by the city and her success, he returned home to make something of himself first. She and Jake have a heart-to-heart talk, and Melanie understands why he never signed their divorce papers.
Andrew arrives to surprise Melanie, but upon learning her true background and that Jake was her husband, he angrily leaves. He later returns, saying he still wants to marry Melanie, and the wedding is immediately set in motion. Melanie's New York friends arrive for the event. While visiting a nearby restaurant/resort with a glassblowing gallery, they admire the glass sculptures that are similar to ones they have seen in New York. Melanie realizes Jake is the artist and he owns the resort.
During Melanie and Andrew's wedding at the Carmichael estate, a lawyer arrives and halts the ceremony. He has the divorce papers, which Melanie never signed. Melanie realizes she still loves Jake and cancels the wedding. She and Andrew wish each other well, though Kate berates Andrew and insults Melanie, her family, and the entire town, for which Melanie punches her in the jaw. Melanie finds Jake at the beach planting lightning rods in the sand during a rainstorm to create more glass sculptures. She says they are still married. They return to what would have been Melanie and Andrew's reception, and finally have their first dance as husband and wife.
A mid-credits sequence shows that they have a baby daughter, Melanie continues to thrive as a designer, and Jake opens a "Deep South Glass" franchise in New York. Andrew is engaged to a girl named Erin Vanderbilt.
Reese Witherspoon as Melanie Carmichael/Smooter
Dakota Fanning as young Melanie Carmichael
Josh Lucas as Jake Perry
Thomas Curtis as young Jake Perry
Patrick Dempsey as Andrew Hennings
Candice Bergen as Mayor Kate Hennings
Mary Kay Place as Pearl Smooter
Fred Ward as Earl Smooter
Jean Smart as Stella Kay Perry
Ethan Embry as Bobby Ray
Melanie Lynskey as Lurlynn
Courtney Gains as Sheriff Wade
Mary Lynn Rajskub as Dorothea
Rhona Mitra as Tabatha Wadmore-Smith
Nathan Lee Graham as Frederick Montana
Sean Bridgers as Eldon
Fleet Cooper as Clinton
Kevin Sussman as Barry Lowenstein
Mark Skinner as Bruno
Michelle Krusiec as Pan
Phil Cater as Pablo
Michael Snow as Devin
Bob Penny as Wallace Buford
Mark Matkevich as Tom Darovsic
Lee Roy Giles as Eugene the guard
Afemo Omilami as Jimmy Lee
Kevin Hagan as Jimmy the driver
Dennis Ryan as reporter
Jim O'Connor as reporter
Leslie Hendrix as reporter
Mark Oliver as guard #2
Colin Ford as Clinton Jr. (uncredited)
Jason Guy as photographer at the red carpet (uncredited)
Andrew Prine as Sheriff Holt (uncredited)