Richard Curtis scripts Netflix's animated picture

That Christmas begins with a familiar dilemma: it's Christmas Eve and Santa Claus faces treacherous weather while delivering his long-awaited gifts.

We meet the benevolent legend, voiced here by Brian Cox, as he rides through a nasty winter storm with high winds and poor visibility. A terrible illness left him with only one reindeer (Guz Khan) to pull his sleigh. The tension between the two is so high that Santa Claus, at one point, threatens to get a self-driving vehicle next winter. But even if the odds are not in our hero's favor, the happiness of children everywhere – and especially those in the fictional English coastal town where the story is set – depends on him outperforming them.

Premiered at the BFI London Film Festival, That Christmas is a charming animation by Locksmith (Ron was wrong) which is poised to become a classic. It can be easy to sneer at the arrival of a new Christmas movie. True holiday cheer is hard to conjure, and if you're not the intended audience for Hallmark-type saccharine, the holiday dish probably inspires more exasperation than joy. But this one, adapted by Peter Souter and Richard Curtis from the latter's series of children's books, cleverly avoids the usual saccharine by grounding its whimsical story in the real, biting emotions of life.

Directed by Simon Otto (How to train your dragon), the Netflix feature boasts a strong voice cast and a narrative that successfully finds the middle ground between the winking self-awareness and the suspension of disbelief that fuels all Christmas tales. It's Curtis' first foray into animation, and while the characters are digitally rendered, the story draws on the same authentic energies that made his early work so beloved.

Similar to Love, actually (who makes a funny cameo here), That Christmas observe how the lives of multiple people are parallel and intersect. Father Christmas, in voice-over narration, introduces us to Wellington-on-Sea, a close-knit multicultural English enclave that became the center of one of its busiest Christmases. His story begins a few days before the holidays, when the local children put on a show Three wise womena rebellious and progressive version of a play about the Three Kings.

A collaboration between outspoken 15-year-old director Bernadette (India Brown) and her cranky friend Sam (Zazie Hayhurst), the production includes contemporary covers and replaces shepherds with organic vegetable farmers. It is a refutation of the past and a vision of a radical, more sustainable future. It's also a chaotic mess that doubles as an effective showcase for the main characters in this intertwining narrative.

Danny (Jack Wisniewski), a newcomer to town, is the center around which all other plots orbit. She has a crush on Sam, but their respective personalities – she's anxious, he's shy – mean they may be doomed to long-distance love.

When he's not daydreaming about Sam, young Danny fantasizes about Christmas with his father, who he expects to visit for the holidays. The boy's life is organized around distraction, especially because his mother (Jodie Whittaker) works long days and nights as a nurse. There's a nice thread there That Christmas which ultimately focuses on a budding friendship between Danny and his neighbor and teacher, Mrs. Trapper (Fiona Shaw), a hot-tempered woman who makes the Grinch seem lovable.

As Danny struggles with isolation and the emotional fallout of his parents' divorce, Sam fears that his twin sister Charlie, on a mission to cause trouble, will ruin his chances of receiving presents from Santa. The pranks Charlie pulls, which mortify his sister and exasperate their parents (Rosie Cavaliero and Andy Nyman), include some of the film's punchiest scenes and funniest lines, helping to maintain its overall comedic tone.

In another part of town, Bernadette and her little sister Evie (Bronte Smith) are preparing for the holidays with their parents, the hilarious McNutts (Lolly Adefope and Rhys Darby), and some family friends. Along with the commitment of the performances, the diversity of these characters – both phenotypically and in terms of personality – helps enliven That Christmasmaking it a film that can still pleasantly surprise.

The action really gets going after Bernedette's parents and their friends (Mrs. Mulji, voiced by Sindhu Vee, and the Forrests, voiced by Alex MacQueen and Katherine Parkinson) go out of town for a wedding. It's a brave choice for someone to hold their wedding so close to Christmas, but adults, eager to spend some time away from their children, rush off the island.

It didn't matter that school was canceled because of a blowout snow or gray fog in the distance. It is only after the wedding, when the parents discover that the ferry is no longer working, that they realize the reality before them: the weather conditions will make the return more difficult, perhaps forcing them to miss Christmas with their families.

For all its narrative concerns, That Christmas it rarely feels like it's compromising any set of characters or their arcs. There are moments where you can tell the film is an amalgamation of different books, but, for the most part, Curtis and Souter's script moves confidently between the threads. This dexterity reinforces the impression that this Christmas story is truly a community portrait. The effort to capture the essence of a neighborhood makes it easier to accept more fantastical elements or moments that tend towards the artificial.

Otto makes the most of the 91 minutes of runtime, then That Christmas it never feels abruptly stimulated or disconnected. Attention to detail – from the diligence with which the man who takes care of the lighthouse (Bill Nighy) changes the town bulletin every day, to the long simmering feuds between several citizens – makes the film engaging and this fictional village alive.