After the death of their father, siblings Kate and Teddy are struggling to feel happy during Christmas. Luckily, their widowed mother Claire is a dedicated and loving parent to them both. The kids still believe in Santa and Kate even convinces her cynical brother to join her in a plan to capture proof on camera of him visiting their house. However, their plan backfires when they startle him and cause his sleigh to crash, losing his magical hat and a bag of presents. It’s up to them, Kate’s reindeer, and some elves to find the presents and save Christmas before time runs out.
The movie quickly catches up with the rest of the Pierce family, with youngest daughter Kate rewatching home videos from her dad to feel closer to him. Her older sister Teddy ridicules her for this, but the two love each other and want the best for each other despite their differences. Their mom struggles to keep up with work while juggling the children and keeping them from killing each other.
At the North Pole, Santa sees on his smartwatch that he only has an hour left to finish his deliveries and needs the kids’ help to get it done. Kate and Teddy agree to help, but Santa’s sleigh breaks down in Chicago. He teleports to the bar where Kate and Teddy are hiding, stealing the car from the bartender (while morally squaring it with him first). When police officers Dave Poveda and Mikey Jameson arrive, they arrest Santa but he gets them to bail him out of jail by singing a rock song in his holding cell. Then he gives Kate and Teddy his hat as a memento, showing that they don’t need it anymore.