‘Jaw-dropping’ horror film The Substance premieres at the Cannes Film Festival

Demi Moore plays a has-been actress, Elisabeth Sparkle, in The Substance. Photo / Youtube, @MUBI

In Coralie Fargeat’s riveting film, Demi Moore’s has-been actress clones herself in an attempt to stay relevant – with sinister results.

Demi Moore may not have been born to play her astonishing role in The Substance, but she could certainly have been christened with it in mind. The has-been actress she plays, one Elisabeth Sparkle, uses a serum injection to split herself in two, aiming to resurrect her career as a younger, more beautiful clone (Margaret Qualley). Christened “Sue”, this latter literally crawls out of Elisabeth’s spine; but though they were meant to co-exist happily, Sue’s narcissism threatens to make Elisabeth, like the portrait in the attic, wither away.

If that science-fictional premise sounds wild, you haven’t heard the half of it. The Substance is a humdinger of a satirical horror-thriller, by turns hilarious, affecting and jaw-droppingly grotesque. It’s exactly the jolt of extravagantly stylised genre energy the Cannes Film Festival needed at this midway point, and Moore, making a mighty comeback, seizes the role as if her life depended on it.

Masterminding this eerily Day-Glo nightmare is the French writer-director Coralie Fargeat, almost certain to take home a major prize. Her vision is so savagely excessive that it has a hallucinatory, how-is-this-even-happening quality. The themes aren’t subtle: impossible beauty standards, fear of ageing, internalised misogyny (and the straightforward kind). In Fargeat’s heightened parody of Los Angeles, the male characters are piggy slimeballs, and the perfect body a tyrannical icon.

Elisabeth refuses to be put out to pasture. She has a star on the Hollywood Walk of Fame, which, in Fargeat’s bravura opening, we see being implanted, then trampled on across the decades. She even won an Oscar once, though no one remembers which film it was for. Now past 50, she’s let go by a sulphurous TV exec (Dennis Quaid, gleefully horrible) from her dance workout show, Sparkle Your Life, because he wants to reignite the ratings with a fresh face.

Yet that fresh face could be Elisabeth’s own – if she experiments with a hush-hush medical programme, known as The Substance, which has strict rules. Once your younger self pops out, you must share consciousness by turns: one week on, one week off. In the first of many escalatingly outre effects sequences, Qualley’s Sue is born, and rapidly seizes Elisabeth’s spotlight; the thrusting wannabe doesn’t fancy switching back.

The ensuing mano-a-mano between ingenue and hag has all the spite of Death Becomes Her, if the leads were duelling sides of one person. The gross-out levels climb: when Sue steals extra time from poor Elisabeth, the first side-effect is a withered finger, more than horrible enough by itself to make us dread what the rest of her will eventually look like.

Fargeat makes various unmissable homages, to Vertigo and The Shining in particular. It’s the casting of Moore, though, and her willingness to denude herself at 61 – emotionally, as well as physically – that gives The Substance a startling connection with its themes. Not for 30 years has she owned a film with anything like this certitude. Watching her confront the Demi Moore in the mirror, and do it so mercilessly, is extraordinary.