Arnaud Desplechin’s first international success came with his third feature, the nearly three-hour Comment Je me Disputé… Ma Vie Sexuelle (even the title was long). You expected a terrible bore – a group of middle-class philosophy students talk, smoke, talk, talk, smoke, have sex, drink and talk and smoke some more – but somehow it managed to be one of the most emotionally affecting movies of 1996.

That film may have been about a bunch of students, but its subject was really how friends can become a surrogate family, a theme he has continued to explore. Esther Kahn was also about a surrogate family, while 2004’s emotionally brutal Rois et Reine, was, it turned out, about his now ex-wife’s family (as she famously revealed in a book she wrote about how the director had stolen her life for the film). His latest film, Un Conte de Noël (A Christmas Tale), continues Desplechin’s familial quest.

Set in the northern French town of Roubaix (surely not by chance, it is also Desplechin’s hometown), Un Conte dives into the world of the deeply dysfunctional Vuillards. The aptly named Junon (Catherine Deneuve, wonderful once again), a matriarch who freely admits to being a bad mother who has never loved her children, discovers that she has lymphoma and only a bone-marrow transplant can save her (in one funny scene her son-in-law explains in great detail the statistical formulae needed to reveal that the transplant will add exactly 1.7 years to her life). The disease’s diagnosis means, of course, finding a compatible donor. Tests reveal two suitable candidates: her daughter’s mentally troubled 15-year-old son and her own mentally troubled son Henri (Mathieu Almaric). Cue much discussion and not a little recrimination.

As always with Desplechin, the bare bones of the plot actually reveal very little about the actual film. His great talent as a storyteller (ably aided by co-writer Emmanuel Bourdieu) lies in the way he manages to take the viewer deep inside the dynamics of his characters and their relationships to reveal the motives and hidden hurts that make up any human being and every family. What makes him a great director, however, is how he uses filmmaking techniques to do it; his films may be talky (and boy, are they), but they’re never simply filmed discussions.

With the help of France’s best cinematographer, Éric Gautier, Desplechin plays with forms and genres, timeframes and music (almost an extra character) to take us on a journey inside his characters. He’s not afraid to experiment. The film’s structure moves backward and forward in time, yet it never becomes confusing: Desplechin has total control.

He also has characters directly address the camera, which is often a horrid postmodern “we all know we’re in a film and you’re the viewer” gimmick, but he dares to play it straight, so instead of being annoyed you feel privileged to hear their thoughts and share their feelings. You feel as if you’re their friend.

It’s like much of Desplechin: it shouldn’t work, yet it does, thanks to a striking emotional honesty and an adult acceptance that people are never either good or bad, they just are. This means that he is unwilling to fall back onto easy dramatic devices: like real people, his characters don’t change – they are who they are – and while they may have moments of grace they don’t – as so often happens in, shall we say, less intelligent cinema – suddenly become somebody else. The drama is in the (often cruel) details.

With a cast featuring many of France’s best actors (Emmanuelle Devos, Hippolyte Girardot, Chiara Mastroianni), Un Conte de Noël is beautifully played, funny, honest, heartfelt and smart. The best compliment you can pay is that after two-and-a-half hours in the company of the Vuillards, you walk out and want to head straight back and see them again.