The French director Jean-Pierre Jeunet takes on the international arms industry with whimsy, elaborately staged pranks and more than a hint, horror of horrors, of mime.

By rights, the result should be unwatchable, yet as the director has already demonstrated with Amélie and Delicatessen, his is the kind of all-enveloping vision that sweeps up all but the most militant fans of unvarnished realism.

In Micmacs, which screened yesterday at the Times BFI London Film Festival, the orchestrator of impossibly complicated fantasies dials down his fevered imagination just a touch. The story unfolds against a backdrop that is more or less recognisable as the real world, or as close to the real world as Jeunet is prepared to venture.

In a giddy extended opening sequence, the film whizzes through the tragedies of one man’s life. In 1979, his soldier father is killed while attempting to disarm a mine. His mother does not take the news well. The last we see of her is her exit, carted off by men in white coats. The child is sent to a Roman Catholic orphanage. Fast forward: the boy, Bazil (Dany Boon), is now an adult, whiling away the hours as a video store clerk by watching The Big Sleep. A shootout in the road outside leaves a stray bullet lodged in his brain. Doctors decide to leave it, trading the risk of sudden death against the risk of life as a vegetable should the operation go wrong.

It is here that the film proper starts. Bazil is adopted by a band of eccentric misfits who collect, revamp and recycle the discarded scrap of other people’s lives. These junkyard geniuses are Bazil’s backup in his plan to take down two rival arms companies, one responsible for the mine that killed his father, the other the one that manufactured the bullet in his head.

Jeunet’s sabotage of the French defence industry is part Jacques Tati (dialogue is minimal, physical comedy is honed to perfection) and part Looney Tunes.

The gang employ giant magnets and human cannons: you half expect an Acme anvil to plummet from the sky. There is also a nod to the films of the 1940s in Jeunet’s soundtrack choices.

The main problem is that in this wacky plot packed with outlandish gadgets, the characters are little more than props themselves. Each is defined by a single quirk. Buster (Jeunet regular Dominique Pinon) breaks world records; Calculator (Marie-Julie Baup) is a maths whizz; Elastic Girl (Julie Ferrier) is a feisty contortionist. As such, the film lacks the emotional swell of Amélie. Still, with its loopy, idiosyncratic take on an anti-corporate message, Micmacs might find itself in tune with current audience moods.

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