It begins with the precision of a chess game: a pair of shoes, a yellow handbag trailing in the air, a descriptive voice over; and ends in Dadaist freefall, culminating in a child’s single baffling, but brilliantly enigmatic line. Everything in between makes about as much sense as Alice in Wonderland – which of course makes a great deal of sense depending on your perspective. Warning is sounded in the opening images of grass growing up through cracks in the pavement – symbolizing, perhaps, wayward human nature and unbridled imagination breaking through the hard shell of reality? One message is certain: expect the unexpected.

Alain Resnais initially found himself drawn to the writing of Christain Gailly – on whose novel, L’Incident, the film was based – because of its musicality, and there’s undoubtedly something akin to an improvised jazz riff about Wild Grass. That doesn’t mean that the direction is undisciplined or out of control. Far from it. A rigorous precision underlies the foreground design. The spontaneity comes from the fluctuating tone and meandering storyline. Though he may hit the odd bum note, Resnais is unconcerned, as long as he can express himself without restriction. This is a movie after all, he seems to be saying. Why should it unfold in a way we’ve come to expect?

But what are we to make of the characters that inhabit this curious world? Beneath his placid exterior, Georges hides an intense inner life somewhere between that of a nervous adolescent and a tortured sex killer. Wracked by indecision and obscure impulses, he stumbles through the story like a sleepwalker with a guilty conscience and a short fuse. And what of Marguerite – dentist, aviator and the object of Georges’s obsession? At first she understandably recoils from his advances, but just as he desists, so she reignites their strange courtship. Rejected, she turns up at his house uninvited and begins taking out her frustrations on her dental patients. Both appear driven by, as producer Jean-Louis Livi put it, a “desire to desire”. Toying with their compulsions, they try to rationalize them, to fight them, but are, in Resnais’ own words, “incapable of resisting the desire to carry out irrational acts, displaying incredible vitality in what we can look on as a headlong rush into confusion”. The supporting characters are equally peculiar, even the seemingly level-headed Suzanne appears unconcerned by the relationship that develops between her husband and a strange woman. As for the two cops, they appear to have stepped from the pages of a Tintin story by way of Franz Kafka.

With so many unanswered questions it is reassuring to find ourselves in the hands of a master filmmaker. Resnais directs with the verve and flamboyance of an MGM musical, his camera gliding sensuously and seamlessly from one scene to the next – though the music itself is more David Lynch than Stanley Donan (the composer Mark Snow actually created the music for cult Sci-Fi TV series The X Files). There’s a deliberate artificiality to the colour, lighting and décor schemes – “I really like it when a film looks like a film,” Resnais stated in a recent interview. This theatricality is moderated by a perceptive observation of character interaction and the kind of comedy of manners reminiscent of the plays of Alan Ayckbourn, whose work Resnais has twice before adapted for the screen.

At the age of 87, one might imagine that Alain Resnais would be content to rest on his laurels as other celebrated auteurs have done in their old age. However, like compatriots Eric Rohmer, Agnes Varda, Jean-Luc Godard, and the other New Wave directors, he continues to explore new forms of expression, avoiding genre conventions, while referencing cinema’s golden past. Wild Grass, while perhaps not on par with the best of his earlier work, is nonetheless a thought-provoking, sometimes funny, sometimes downright weird, late addition to his unique body of work.