An old wound. A festive night. And a chance encounter that could change everything.

Kang Min-jun, a meticulous head of security at one of Seoul's most prestigious malls, is a man who lives by the rules. His life, a carefully constructed fortress of routine and predictability, leaves no room for mistakes—or Christmas cheer. For him, Christmas Eve is just another night, a job to be done.

But for Han Ji-hye, a ghost from his past and a notorious shoplifter known as the "Christmas Ghost," it's a night of quiet rebellion. She's in the mall for one reason: to revisit a secret world she once shared with her late mother. But her mission is interrupted when the mall's security shutters come down, trapping them both inside.

Now, with a mall on lockdown and a city asleep under a blanket of snow, Min-jun and Ji-hye are forced into an unlikely truce. As they wait for help, they confront not only each other's hidden stories but also a connection that runs deeper than they ever imagined.

Will a night of unexpected chaos lead to a holiday miracle, or will the ghosts of their past keep them from a future they never knew they wanted?