In the early ’70s, legendary French filmmaker François Truffaut circled a screenplay penned by Jean Gruault (who collaborated with Truffaut on classic Jules et Jim), but eventually abandoned the project. Forty years later, Valérie Donzelli (whose Declaration of War opened the Critics’ Week four years ago) rewrote it together with Jérémie Elkaïm, who also plays the male half of the titular pair, to create Marguerite & Julien. How this landed in the main competition is anyone’s guess, but this film is a misfire of epic proportions.

It is a fable about two siblings, Marguerite and Julien, children of French aristocracy, who have been attracted to each other since early childhood. Their parents, sensing something unnatural is developing, send Julien and his brother away to a boarding school, but when he returns after many years (in which they have grown into Anaïs Demoustier and the already-mentioned Elkaïm), their passion is ignited for real, and they give in to their forbidden love. Marguerite is married off to separate the two, but true love finds a way, of course.

The screenplay is based on a true story about an early 17th century brother and sister (who were eventually executed for their incest), and the plot could conceivably make a good, somewhat risky tale of family love gone too far. Marguerite & Julien, however, is not that film. And the blame for that can be placed squarely in the corner of actress-turned-(unfortunately?)-director Donzelli, who deems it necessary to infuse the story with all sorts of hoopla and nonsense that the film really doesn’t need. Take for instance the many anachronisms: for all intents and purposes, the film is set in the 17th century, but Donzelli doesn’t shy away from having radios, cars, and even helicopters in the film, and for no apparent reason. If we really strain ourselves, it might be some statement that a love between siblings like this is still forbidden in our times, but then we would be really gentle to the director, and we don’t want to be. It’s like a Wes Anderson film, only without the wit and a point, and the willingness to take it all the way. There are also visual tricks applied, like scenes starting from a fake freeze frame (with actors just standing still; very Truffaut, but unlike Truffaut very dull), or a photo montage late in the film of the couple’s arrest that is jarringly out of place.

And then there’s the framing device: the story is actually told to young children at an orphanage, and even forgetting about the fact that neither the older girls who tell the story, nor the young girls who hang from their lips, think there’s anything wrong about an incest story, the simultaneously amusing and baffling highlight is that while the storytelling device starts the story and returns several times, it is abandoned somewhere before the final act, never to be heard of again. It is as pointless as the rest of the bag of tricks Donzelli hurls at the screen, trying to mask that she doesn’t have a clue how to make this story compelling.

Unfortunately for her, the actors don’t help her out in any way either. Anaïs Demoustier is not in best form, and Elkaïm is as dull as dishwater. Frédéric Pierrot as the father of Marguerite and Julien seems to think he is in a comedy (which this unintentionally is, but I don’t think he was told that on set), and Geraldine Chaplin amps up the scenery chewing as Marguerite’s scowling mother-in-law. In short, the performances are, like the film, all over the place.

The film has serious pacing problems, spending way too much time on the setup, and there are some glaring editing issues as well, with scenes being cut off at inappropriate moments (a dramatic scene with the mother, played by Aurélia Petit, late in the film provides an extremely bad example). Despite the anachronisms, production design work is on the whole sumptuous enough to make an impression, and the lensing by Céline Bozon provides a couple of striking images, especially in night scenes. But none of this can save the film from being an incongruous mess that lacks aim. For a story about passion, it feels too artificial and lifeless to make any impression. Marguerite & Julien is the worst film in this year’s Cannes competition, perhaps even in the last five years, its inclusion a mystery for the ages.