Mandibles review – bizarre giant-fly comedy runs out of sugar

In the wild old days of the film festival circuit, directors, writers and hangers-on liked to end each day with drunken discussions about the movies they’d seen. They’d say what they’d liked and what they hadn’t, and the things they’d have done better if it was their story to tell. Occasionally, around the time the third bottle was brought out, they’d brainstorm daft ideas: the sort of idiotic, joke conceit that sounds great at 1am and less good the next morning when the hangover has kicked in. That culture is conspicuously absent from this year’s masked, distanced Venice. But incredibly, it appears that one of those wild notions has now fled the bar, taken shape and grown legs. And wings.

Clocking in at a little over an hour, Mandibles is a rollicking, rambunctious tequila-dream of a movie, written and directed by Quentin Dupieux, whose superior Deerskin premiered at Cannes last year. It’s about Manu and Jean-Gab (Gregoire Ludig and David Marsais), two dopey deadbeats who steal a rustbucket Mercedes to run a mysterious - and surely illegal - errand up the coastline. On the way, they’re disturbed by a noise in the boot of the car. “Maybe it’s a hair-dryer,” Jean-Gab says hopefully.

The thing in the boot is not a hair-dryer. It is, in fact, a giant fly with orange eyes the size of basketballs. This gives Jean-Gab an idea. It’s the sort of idea we’d most likely all have upon first throwing open the boot of the car. He wants to train the fly like a monkey and send it off to rob banks.

At this stage of the event, the Venice audience is in need of a little light relief and it rose to embrace Mandibles as you might a long-lost college buddy (the one who always brought the best grass and a backstage pass for the gig). Manu and Jean-Gab are a pair of anti-heroes so stupid they can’t cook a simple meal without burning down the caravan, so one wonders how they’re ever going to train a giant fly to make them millionaires. Still, it’s fun to watch them careering around the scrubbier bits of southern France, hatching ludicrous plans and performing whip-lashing double-takes. They reminded me of Patrick Dewaere and Gerard Depardieu in Bertrand Blier’s Les Valseuses.

The inherent peril of the drunken 1am idea for a movie, though, is that the wacky concept is pretty much the whole deal. Once you’ve opened the boot and marvelled at the contents, it’s hard to work out where a film goes from there, except round in circles, trying to find fresh gags in the material or more sugar to sustain it.

In a big house in the hills, Manu and Jean-Gab meet Agnes. She’s played by Adèle Exarchopoulos, who was so good in Blue Is the Warmest Colour but has a rougher ride here. Agnes, we are told, has injured her brain in a skiing accident and Exarchopoulos plays her at top volume, screaming every line, taking offence at every turn; playing disability for belly-laughs as though she’s auditioning for Benny Hill. Barrelling into the master bedroom one morning, Agnes sees the bug and stops dead from the shock. But the girl has a screw loose, so who’s going to believe Agnes?

It’s funny - the rogue elements that strain credibility and risk breaking a movie. Turns out I’m totally on board with a giant fly in the boot. It’s dumb, bellowing Agnes who finally blows out the film’s levels.

• Mandibles is released on 17 September in cinemas and on 20 September on digital platforms.