It’s also, unfortunately, pretty boring. Silly, baggily structured and numbingly long, the film starts slowly, with one of Susie’s fellow students (Chloë Grace Moretz) visiting her aged Jewish-German therapist and babbling some clumsy exposition about the mysterious goings on at the school. It gets even slower after that. The screenplay establishes early on that Blanc and her colleagues are witches, so there is no mystery to speak of. And while it is quite funny to see them smoking and reading newspapers in the staffroom as they grumble about the coven’s politics (they’re probably writing application letters to Hogwarts, too), none of the witches is interesting as a person. Nope, not even the one played by Swinton. As for Susie, she doesn’t seem bothered by what’s happening – not that much is happening – so you don’t feel the tension you normally would for a protagonist who shares her lodgings with a gang of homicidal maniacs.

In fact, Susie has nothing to do in the film except go to her dance classes, and so the therapist becomes the de facto protagonist in her place. He is the one who investigates the disappearance of Moretz’s character, and he is the one with a fascinating, tragic back story. But Guadagnino has made the regrettable decision to have this old German man played by a well-known younger actor – I won’t say who – masked in prosthetic make-up. You can admire the audacious trickery, but it doesn’t serve any obvious purpose apart from distracting you from what he is saying. The same goes for the music, to an extent. Suspiria is the first film to be scored by Radiohead’s Thom Yorke, which is quite a coup, but whenever you hear him warbling, you think, “Ooh, that’s Thom Yorke!”

All of the above is a roundabout way of saying that Suspira is just not very scary. I expected to be peering at the screen between splayed fingers, but instead I was peering at my watch. One gruesome scene will be adored by fans of Cronenberg-ish bone-crunching body-horror, and there is a witches’ sabbath that is so gloriously over the top it must have had Argento chuckling. But, those scenes aside, most of the frightening parts are confined to dream sequences. They may well have been inserted to stop viewers drifting into a dream state of their own.

★★☆☆☆

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