Kate Pierce, now a cynical teen, is unexpectedly reunited with Santa Claus when a mysterious troublemaker threatens to cancel Christmas--forever.
While on Christmas vacation in Cancun with their respective mom and dad, a true-Santa-believing girl and a boy are kidnapped by a rebellious Santa-hater as a plot for him to get into Santa's Village at the North Pole and destroy it. The kids are saved by Santa and taken to the elf-populated Santa's Village and Mrs. Claus, where they get a tour of the place, dinner, and bedtime story while the Santa-hater starts his sabotage.—Scott Filtenborg
Two years have passed since the events of the last film. Kate Pierce (Darby Camp) is now a cynical pre-teen who is unhappy spending a family Christmas in Cancún, Mexico with her mom Claire (Kimberly Williams-Paisley), her brother Teddy (Judah Lewis), her mom's new boyfriend Bob (Tyrese Gibson), and his son Jack (Jahzir Bruno). She wants to be back home where it's snowing and more like a real Christmas. Kate decides to run away and get an early flight back home to Boston. She catches a shuttle that Jack sneaks on to. They are unexpectedly transported to the North Pole by the driver Belsnickel (Julian Dennison), a nefarious Christmas elf.
Kate and Jack are discovered and saved by Santa Claus (Kurt Russell) who brings them back to his house and Mrs. Claus (Goldie Hawn). The Clauses give the kids a grand tour of their village and all it has to offer. The four of them go back to the house for dinner. Jack and Kate go to bed as Belsnickel and his follower Speck (Debi Derryberry) begin an attempt to destroy the village.
Mrs. Claus tells the kids the origin story of Santa in Turkey and how he saved the elves from extinction, and received the Star of Bethlehem, a magical artifact that stops time in and provides power to Santa's Village. The Claus' adopted Belsnickel. As he grew up and they had less time for him, he became naughty, causing him to be transformed into a human as a curse, and ran away.
Belsnickel releases Jola, a yule cat, into the reindeer pen, injuring Dasher. Belsnickel releases a potion into the village that cause the elves to go insane. He steals the Star of Bethlehem on top of the village's Christmas tree. Santa and the others confront him. Santa attempts to take the star back and in the struggle between him and Belsnickel it is accidentally destroyed, causing the power to go out in the village. The maddened elves start a snowball fight that gives Belsnickel time to escape.
Santa and Kate leave for Turkey in order to get the forest elves led by Hakan (Malcolm McDowell) to build a new star. Jack leaves to get a root to cure the crazed elves while Mrs. Claus stays behind to tend to Dasher. Kate and Santa find the elves who build a casing for a new star and Santa captures the power of the Star of Bethlehem inside it.
While flying back to the village, Belsnickel catches up to them on a sleigh pulled by his jackalotes (a hybrid of a jackal and a coyote) which he created, steals the star so he can stop himself from aging long enough to figure out how to replace Santa, and transports them back to 1990 Boston via a time-travel device he planted on Santa's sleigh. Jack finds the root and brings it back to Mrs. Claus. Kate attempts to buy AAA batteries for Belsnickel's time travel device, which she and Santa now possess, at the Boston airport to transport her and Santa back to the future. However, she is detained by an airport security member (Patrick Gallagher) due to apparent counterfeit (the money was marked 2020), Kate is taken to a locked security room of kids who have lost their parents. Kate is upset about her wrongdoings at Cancun, another kid, Doug (Sunny Suljic) recomforts Kate and helps her escape the room, after Kate joins Santa, she realizes Doug Pierce is her late father. With help from a worker named Grace (Darlene Love), Santa gets everybody singing a Christmas song as the weather clears up. With Christmas spirit high enough for the sleigh to fly, Santa puts the batteries in and they transport back and recover the star.
Mrs. Claus makes the root into a powder. Jack fights his way to the snow cannons, places the powder inside, and shoots it onto the elves, curing them. Santa and Kate race back to the village evading Belsnickel as he chases them. Mrs. Claus throws an explosive gingerbread cookie in between both sleighs before they can collide in a game of chicken. Dasher recovers and assists Santa in defeating Jola, the latter hurling the yule cat out of the village. Kate places the star on top of the tree, restoring power to the village. Santa gives Belsnickel the first toy they built together, and Belsnickel reconciles with them, transforming back into an elf.
Santa flies Kate and Jack back to Cancún where they inform an excited Teddy about their adventure and Kate becomes more accepting of Bob.
In the final scene, Kate's family and everyone at the North Pole sing "O Christmas Tree".
