A holiday family gathering. A terminal illness. Bitter resentments and feuds. Secrets revealed. Relationships kindled and others in a state of flux. If all of this sounds overly familiar and potentially treacly, fear not. Director Arnaud Desplechin's French-language "A Christmas Tale" ("Un Conte de Noël") treats its characters and their lives with an uncommonly raw and complicated realism. The film uses the days leading up to Christmas as a backdrop rather than a gimmick to sell tickets or an excuse to give viewers the warm and fuzzies. Poignant and humane though it may be, the picture refuses to compromise when it comes to depicting the conflicts and dysfunctions of a family seemingly held captive, whether they want to believe it or not, by the death of their first-born nearly forty years earlier.

It makes sense that Joseph Vuillard's short life would be acted out by marionette puppets in the opening scene of "A Christmas Tale," since the childlike visage is very much in tune with his own eternal youth. Stricken with cancer at only four years old, Joseph's parents, Junon (Catherine Deneuve) and Abel (Jean-Paul Roussillon), birthed a second son, Henri (Mathieu Amalric), in the hopes that his DNA would be able to save him. It did not, and the cloud over Joseph's passing has never dissipated. Now in the present, and with Junon recently diagnosed with degenerative cancer, the extended Vuillard family regroups for the first time in five years to spend Christmas together.

As Junon's children—eldest Elizabeth (Anne Consigny), black sheep Henri, and youngest Ivan (Melvil Poupaud)—and Elizabeth's troubled teenage son Paull (Emile Berling) test to see if their bone marrow is compatible for a transplant she will need, Elizabeth finds herself troubled by coming face to face with alcoholic, irresponsible Henri after years of cutting ties with him. Also joining the family reunion are Elizabeth's husband Claude (Hippolyte Girardot); Ivan's wife Sylvia (Chiara Mastroianni) and their two young boys Basile (Thomas Obled) and Baptiste (Clement Obled); Henri's new Jewish girlfriend Faunia (Emmanuelle Devos); and Junon's artist nephew Simon (Laurent Capelluto).

"A Christmas Tale" is an intimate character-based drama with a sprawling ensemble and a 151-minute running time to match. The two-and-a-half hours rush by with nary a moment's thought to its generous length. Some viewers may consider the film a little too esoteric to warm up to, and others not paying close attention may have trouble piecing together who everyone is and their relations to each other. It all promptly works itself out, however, and writer-director Arnaud Desplechin and co-writer Emmanuel Bourdieu are particularly gifted in the way that they craft all the family members and supporting characters as three-dimensional people, free of clichés, and weave them seamlessly into a singular complex tapestry.

By allowing the characters to live their lives without falling into cinematic contrivances, the experience of watching them becomes informative and unpredictable. When Junon nonchalantly tells Henri that she doesn't love him and never has, and Henri responds by returning the gesture, it is disconcerting to the viewer and delivered with such loose gentility that it seems as if they are joking. That they are telling the truth, and at a place where they can come together and speak their minds with such a harsh frankness without being judged, speaks volumes about a relationship that was born out of selfishness—Junon only had Henri as a final attempt to save Joseph—and has never closened in the way a mother and child should. Later, as Henri silently sits on the side of his bed and Faunia catches the look on his face, there is no need for words to explain the guilt and worthlessness he has grown to bottle up inside himself. There is some hope for them, though, and Henri's agreement to donate his bone marrow to Junon is nothing if not generous.

Meanwhile, Elizabeth's reviled feelings for Henri and her sadness as an adult over her own job as a parent—Paull has recently been staying in a psych hospital, just as Henri once did—are things even she can't get to the root of. "It's as if someone died, and I don't know who," Elizabeth tells her shrink. Sylvia is more content—she loves Ivan and has two wonderful children—but she, too, must reconsider all she has ever known when she discovers a secret that explains why Simon, Ivan's sad-eyed friend and cousin, has found it so difficult to break away from the Vuillard family. The way Sylvia handles this knowledge, first in confusion, then anger, before making peace with it, is surprising and affecting. Henri, seeing himself in the lonely Paull, connects with his nephew for the first time and, ultimately, brings him out of his shell. Is Paull suffering from mental problems, or does he just need someone to talk to? Evidence points both ways—in a creepy moment, his reflection in the mirror looks back at him with a chilling grin—but at least he's sane enough to know that the mythical wolf living in the Vuillard cellar is only make-believe.

"A Christmas Tale" is beautifully acted by all—Mathieu Amalric (2008's "Quantum of Solace"), as Henri, and the remarkably understated Jean-Paul Roussillon, as noble and caring patriarchal rock Abel, demand notice—and only uneven when it comes to an eclectic soundtrack and score that a few times overwhelm the narrative content. The bigger dramatic moments in the film are believable, but the occasional fights and arguments cannot hold a candle to the quieter moments of truth permeating out of the scenes. Details, like Abel's ritual of visiting Joseph's grave on Christmas Eve rather than the anniversary of his death, or Junon's trek to midnight mass as most of the family watches "The Ten Commandments" on television, are on the nose about the different personal rituals each family has. Additionally, a heartbreaking scene where the mere sight of photographs hanging on a wall tell a story about the passage of time and the loved ones who come and go is staggering in its unforced emotional impact. In "A Christmas Tale," the Vuillard clan may be flawed and prone to making mistakes, but in those missteps is always the opportunity to learn from them and turn things around. Their futures might not be rosy, but just the suggestion that the healing process has begun is enough.