It’s Christmas Eve, and hopes—comingled with dread—are high. Tristan’s exam results have arrived, but Mrs. Hall convinces Siegfried to delay telling Tristan until after Christmas, lest there’s bad news. She herself is nervously awaiting the arrival of her wayward son Edward, who has said he will visit. She’s put out a gift for him and bought his favorite vegetable, Brussels sprouts, but her constant checking of the door and phone betray her fear that he won’t show.
James is due home to Scotland on Christmas—the same day as Helen’s wedding to Hugh. The whole community is excited for the pig roast Hugh has planned, without Helen’s knowledge. Hugh’s off on a stag night while Helen attends Siegfried’s big Christmas party, where Siegfried plays St. Nick and Tristan reluctantly serves as his elf. Tristan’s duties prevent him from taking advantage of the abundant mistletoe he has hung, but the mistletoe does cause James and Helen to exchanged kisses.
In the middle of the party, James gets a call about a dog struggling to give birth. As he prepares to leave, he finds Helen sitting alone in the dark surgery. She doesn’t want to discuss the wedding, but that’s all anyone else wants to talk about. She asks to join James on his call; he acquiesces against his better judgment.
The dog’s owners are an old married couple who love the chance to chat. James identifies the dog’s issue: one large pup is stuck, blocking the others. Helen helps as he uses forceps to deliver the pup. He fears it won’t survive, but tries to revive it as Helen watches. He gives it to its mother, who manages to lick some life into it as everyone watches, James holding the hand Helen has placed on his shoulder.
Back at the party, Siegfried would like to have his own intimate moment with Dorothy, but he’s too nervous to even interact with her. Tristan pulls him away to look at the nativity play’s ailing donkey—Maggie’s young brother David has quietly asked Tristan for help. But Siegfried is too agitated to be useful.
Tristan sends Siegfried away and tries a gentler approach with the shy David, comforting him and explaining how he copes with his own shyness. David finally admits that the donkey ate mistletoe. Tristan sends him and the other children who have gathered back to the party while he treats the donkey. David emerges from his shell, and later tells Maggie Tristan made the donkey better.
Siegfried again appears, asking Tristan for advice on how to talk to Dorothy. Tristan gloats; Siegfried finds his suggestions unhelpful. Only as Dorothy is leaving the party does Siegfried find success, as she asks him to narrate how the younger, more confident Siegfried would have approached her. They kiss and she promises she’ll be coming around more often. She also asks Siegfried to take care of Mrs. Hall: Edward never showed.
Siegfried sets off to join Mrs. Hall at church and finds her quietly crying during a hymn. He holds her hand as he joins in singing. After mass, she finally explains her complicated relationship with her son. She caught him stealing from her previous employer and wouldn’t lie to protect him. He was sent to a juvenile center for six months, and has never forgiven her.
Tristan is also melancholy, back at the house. But as he looks forlornly at his mistletoe, Maggie comes in, smiles, and gives him a kiss under a bough. Later, Siegfried gives Tristan his exam results. Even though Tristan wants to wait to open them, Siegfried is too eager: he rips the envelope and proudly announces that Tristan has passed. As Tristan and Mrs. Hall celebrate and leave the room, Siegfried throws the letter in the fire. Tristan’s results—one pass, one fail—burn away.
James and Helen are ready to drive back to town for the night, but a deep fog has descended, making it impossible for them to leave. James calls Mrs. Hall to let her know he and Helen probably won’t make it back until morning; Helen’s father should bring her dress to the surgery and she can get ready there first thing. Mrs. Hall chastises James for bringing Helen along, and warns him not to do anything he might regret.
As the old man of the house snores, the woman talks about their marriage and long-lasting love, as well as the discrimination they faced at first—she’s Black. When Helen goes outside to fetch water, the woman meaningfully asks James if Helen knows. James shakes his head; he has tried to avoid making Helen aware of his love for her. The woman notes that Helen is way out in the boondocks with James the night before her wedding—that tells you something.
The couple goes upstairs to bed, leaving Helen and James alone. They chat about other paths they might have taken and James’s past year in Yorkshire. Helen asks him what he might have done differently; he nearly tells her he loves her. But instead, he advises her to go to sleep: she has a big day tomorrow.
They barely make it to town in time—the car has to be cranked before they can leave. As Helen gets ready, James is lost in thought. He tells Siegfried and Mrs. Hall he’s considering staying for the wedding. They immediately tell him that’s a bad idea. Siegfried loans James the nice car, and James sets off for Scotland.
He drives for a while, then stops at a crossroads and considers. Finally, he turns around. Arriving at the church, he sees everyone leaving. As Tristan and Siegfried walk past, James sadly says, “I missed it.” Tristan responds: “Oh, did you ever.”
James goes inside and finds Helen sitting alone. She softly cries and asks, “What have I done? Hugh didn’t deserve this.” James reassures her that she only called off the marriage because she is kind. “Let’s get you home,” he says.
At Christmas dinner with Siegfried, Tristan, and Mrs. Hall, Tristan asks a burning question: what happened…with the dog’s puppies? Siegfried offers a toast: he’s grateful for everything he has, especially the people, “infuriating as you all are.” He stumbles over the sentiment, and ends with a rousing “Merry bloody Christmas.”