The Substance review: 'Magnificently tasteless' horror comedy is Demi Moore's 'best big-screen role in decades'

The Cannes Film Festival always has a few films which get people talking – and which also get people gasping, wincing, and laughing in disbelief. This year, one of those films is The Substance, a gleefully grisly horror comedy from Coralie Fargeat. The French writer-director didn't hold back on gore and nudity in her debut, Revenge, but that film was positively prudish compared to its outrageous follow-up.

The Substance is a showbiz satire which applies a Charlie Kaufman-ish science-fiction concept to the themes of Sunset Boulevard. Its heroine, played by Demi Moore, is an actress named Elizabeth Sparkle – which gives you some idea of how little Fargeat cares about being subtle. A brilliant opening montage shows Elizabeth's star on the Hollywood Walk of Fame go from being shiny and new to cracked and dirty as the years pass, just as Elizabeth goes from being an Oscar-winning A-lister to the host of a daytime aerobics television show. And even this role is taken from her when her boorish producer, played by Dennis Quaid, announces that it's time for fresh meat.

No one who sees Fargeat's film will forget it

In desperation, Elisabeth undergoes a mysterious DIY cloning process which causes a perky young doppelganger named Sue, played by Margaret Qualley, to emerge from her spine like a chick hatching from an egg. Yes, it's as yucky as it sounds. Both women can't be conscious at the same time, but as long as they make sure that they're out and about for only a week at a time, before swapping places with their other self, then everything will be fine. During Sue's weeks, she can nab Elizabeth's old television job and rise to superstardom, while her progenitor lies comatose in a secret room in her luxury apartment. And then, during Elizabeth's weeks she can... well that's the problem. Elizabeth isn't sure what to do with her time, but she soon feels like the meek Doctor Jekyll to Sue's roving Mr Hyde, or the portrait rotting in the attic while Dorian Gray is having a ball.

Fargeat's twisted tale is good fun, especially if you like to hear squelching, cracking and crunching noises as gruesome things are done to human flesh. (Anyone with a fear of needles should avoid The Substance at all costs.) The film also offers attention-grabbing roles for all three of its stars. Ripping into her best big-screen role in decades, Moore is fearless in parodying her public image, Qualley showcases a wicked sense of humour as Barbie's evil twin, and Quaid hams it up joyously as an obnoxious, flashy-suited impresario. "Who has time to say that," he demands, when he hears that his assistant is named Isabella. He decides to call her "Cindy" instead.

But for the majority of its two-and-a-bit hours, The Substance has lashings of style, but not much – you guessed it – substance. Fargeat is obsessed by the technicalities of cloning - hence all the squelching, cracking and crunching noises – but avoids all discussion of the company that provides it. Her satire is easy and obvious, too. It's no revelation that the entertainment, cosmetics and medical industries profit from fetishising attractive young women, and yet rather than examining the issue any more deeply, Fargeat makes the same rudimentary point over and over again – and she makes that point with leering close-ups of Qualley's naked or semi-naked body. She may object to the way women are judged by their appearances, but appearances are all that these particular women have. We are invited to gaze at how smooth or how lined their skin is, but we aren't shown their hopes or their histories, their friends or their relatives.

As amusing and brightly stylised as it is, then, The Substance comes to feel like a slow and superficial waste of an intriguing premise. But the delirious last half-hour makes it all worthwhile. As Elizabeth and Sue start to get on each other's nerves, the film gets funnier and nastier until it eventually blossoms into a deranged monster movie, awash with fake blood, and boasting body-horror oddities worthy of Fargeat's most obvious influences, David Cronenberg and John Carpenter. And then it goes even further. 

For some viewers, this frenzied finale will be reason enough to treasure The Substance; for others, it will be reason enough to steer well clear. But no one who sees Fargeat's film will forget it. If she had taken it to its magnificently tasteless extreme 15 or 20 minutes sooner, it would have been a cult classic.

-bbc