Practical-minded Paige Pierce has her life in order. She's got a job she loves, teaching English, and is launching a new "Paws and Read" literacy program for struggling students at her school. Despite her dismal dating record, Paige rarely thinks about her old college boyfriend, Dean Burton. Then dreamy Dean surprises her at her school's faculty holiday party, upending her world. When she learns Dean's been hired as their replacement physics teacher, Paige can't help getting stars in her eyes and wondering what her life might have been like if they'd never said goodbye.

With a rare comet passing overhead and the aid of a mysterious holiday market vendor, the universe grants Paige a chance to find out....

The next morning, she wakes up in an alternate reality, greeted by Dean's sunny optimism, their two kids, and a dog. Suddenly in way over her head with myriad household chores, a precocious little girl and a toddler boy who's—yikes—potty training, Paige is desperate to scramble her way back home. Until her heart starts melting under the mistletoe, due to Dean's swoony kisses and the cute shenanigans of their sweet kids and loyal pup, and she finds herself questioning where her home is truly meant to be. Yet the enchantment that's brought her here won't last forever.

With the clock ticking on Christmas magic, can the past be undone?