In the town of Angel Falls, Susan Carpenter, a young widow with a six-year-old son, has decorated her house every Christmas for nine years.  The first years, her husband, Bill, had helped her make Christmas a magical time, and spread the true meaning of Christmas.  And, while the people came in droves to see the lights and hear the carols playing, they also brought donations of food for the food bank.  Meanwhile, Susan, dressed as Mrs. Santa, handed out candy canes to all the children.

When Bill died in a car wreck, Susan carried on alone.  No one in the neighborhood complained about the lights and noise until Don Rawlins moved in across the street four years ago.  He was wealthy and could live anywhere he chose, but he was also accustomed to forcing everyone to do his bidding.  He wanted the lights and music gone from the Carpenter house, and he told her to shut them down.  Though the lights and music went off at ten each night, Rawlins continued to demand she turn them off for good, and Susan continued to refuse to obey.  So, Rawlins enlisted the aid of his godson, Luke Potter, who had a similar Scroogely Christmas spirit.  Luke bought the house next door to Susan and rented it to more Scrooges.

At first, the renters joined Rawlins and Potter in their complaints.  Then, without warning, they moved out, leaving Potter with an empty house on his hands.  Already soured on Christmas, because that was when his parents split up, Potter was furious.  So, when Rawlins offered him financing for his new business in exchange for joining him is suing Susan Carpenter, Potter went for it.

When Susan's sister, Nicole, subbing as Mrs. Santa, was served with the papers, she immediately called her boyfriend, Todd Shelburne, a reporter for the Angel Falls Clarion.  He  promptly wrote an article that painted Luke Potter as the Scrooge of Angel Falls, and set up a legal defense fund to help "Suzi Christmas" keep her lights on.

Meanwhile, Potter's younger brother, Ben, saw a well stacked blonde deliver a singing birthday greeting to a fellow bar patron.  He decided that blonde was just what his brother needed to cheer him up.  Though it wasn't Luke's birthday, Ben hired the blonde to sing to him.  He almost had to call a halt when he found out the blonde was none other than Susan Carpenter, the woman Potter was suing.  But he told her his brother's name was Nicholas Claus, and made the deal.

Ben was right, Susan did cheer up his brother.  Luke Potter decided that, in the guise of Nicholas Claus, employee of Luke Potter, he would take Susan out and prove he was no Scrooge, and in the process, he could convince her to take down some of the lights.

But every time he mentioned Luke Potter to Susan, he set off a virtual volcano.  He also found himself falling in love with Susan and feeling more and more like a heel.  Don Rawlins, once his idol, was beginning to look like the despot he really was to Luke.  To further complicate matters, Potter's mother, Celeste Knight, had fallen in love with Hank Appleby, Susan's father, and neither was aware of who the other one was.

Luke has to pay off Rawlins and withdraw from the suit before he can find happiness with Susan.  But can he do it before she finds out who he is and he ruins the lives of four people?  All I Want for Christmas is the heartwarming tale of a young man who learns the true meaning of Christmas as he also learns how to love.