Avery and Logan, once innocent childhood friends, find themselves drawn together as a couple years later. After nearly 18 years of their initial bond, Avery receives an exciting opportunity to work abroad in England, a chance she wholeheartedly embraces. During her surprise farewell party, however, a drunken Logan misinterprets a suggestion about proposing, believing it to be coming from her father. In a moment filled with raw emotion, Avery lashes out after he unwittingly mentions her late mother, resulting in her declaring she never wants to see him again.
Fast forward a decade, the currents of fate have intertwined their lives once again. Both Avery and Logan are about to meet their significant others' families for the very first time during a pre-Christmas family gathering. It's an ironic twist, as they discover Cam (Avery's boyfriend) and Cassie (Logan's girlfriend) are siblings in the Morgan family, causing immense embarrassment for Avery. She pleads with Logan to keep their shared past under wraps, worried about facing uncomfortable inquiries, particularly from the intimidating matriarch, Erica.
With the family maintaining their tradition of unveiling the annual family portrait, Avery and Logan are dispatched to procure the Christmas tree. Amid the holiday chaos, Avery, who specializes in crafting business proposals, finds herself helping Logan prepare his architecture proposal, which is imminent. In return, he vows to assist her in establishing a better connection with the Morgans.
The entire family attends mass together at 4 p.m., where Avery has volunteered to speak. Earlier in the day, following their tree quest, Avery succumbs to her sweet tooth, munching on gummy bears from the pocket of the youngest Morgan, Callum. However, in a comedic twist, Logan discovers they are actually THC-infused edibles and attempts to inform the priest of her condition, only to find that the altar boy overlooks his warning.
As Avery is called to the front to deliver her speech, she is blindsided by the effects of the edibles, leading her to lose her train of thought. Hallucinating that the statue of Mary is speaking to her, she clumsily merges the birth of Jesus with the lyrics of Kool + the Gang's Celebration. Initially met with incredulous silence, she is pleasantly surprised when a congregation member joins in, turning the mass into an unexpected sing-along, much to everyone's astonishment.
Before Erica can scold her for the chaos, the priest praises Avery for her ability to uplift the congregation. Unfortunately, Avery's evening takes a comical turn as she drifts off to sleep while snacking on Erica's delicious cookies, which prompts an urgent need to frame the family dog for the mishap. As panic ensues over the mini dog’s chocolate allergy, Erica insists on taking it to the vet, setting the stage for a series of humorous escapades.
Avery cleverly accompanies Erica and the dog to the veterinarian's office. Here, she feigns concern while confessing her guilt to the doctor and pleading for his discretion. To maintain her secret, she ends up paying the hefty hospital bill, once she's relieved to have escaped with her secrets intact.
Upon returning home after the vet scare is creatively spun to make Avery appear as a hero, Logan engages her in a private discussion, chastising her for riskily covering up their history. Unbeknownst to them, Callum overhears their conversation, leaving him intrigued enough to ask for Avery’s contact information.
The evening unfolds with both couples taking their relationships out for drinks. A curveball is thrown when Cam's ex, Sophie, makes an unexpected entrance. Avery's life takes another twist when she receives a call from her father's real estate agent asking for a house key. Logan steps up and offers to take her on the drive to her childhood home.
At the nostalgic site, Avery shares her feelings of loss regarding her mother, leaning into Logan for comfort. However, their drive takes an unexpected detour when they have to pick up the inebriated Callum, who suffered the consequences of the evening's indulgences. Back at the house, Logan devotes himself to finalizing his proposal, but soon it becomes apparent that he must cover for Cam, who has returned at an ungodly hour.
As Christmas Eve dinner approaches, secrets begin to unravel. Avery and Logan discover they're both from the same small town, while Sophie throws another surprise by announcing her return. In a chaotic series of gift exchanges among friends and family, the atmosphere quickly turns tense when Logan’s family’s affairs are revealed, with Callum exposing their histories just as Avery feels her carefully laid plans begin to collapse.
Ultimately, Avery's father, Mitchell, unexpectedly returns from a trip and surprises her with the house key, a heartfelt gesture entailing that he believes her homecoming is essential. In a show of mutual support, Avery encourages Erica to present Logan's proposal to someone who could recognize the brilliance of his vision.
The story culminates in Avery's housewarming party, where Logan takes a brave step and asks her to give their romance another chance. With love in their eyes, they express their feelings and share a passionate kiss, signaling their commitment to one another. A year later, we find the couple planning their wedding together, having comfortably settled into their shared lives. They are joined by Logan's boss, Stan, who, with a batch of cookies in hand, arrives unexpectedly, marking the beginning of a new chapter for their intertwined families.
