Think of this as a road trip about two lovers on the run, rather than the cannibal film that nobody wants to see. It isn’t flippant to say this because the film is really about the attraction between two outsiders who share an addiction so taboo they can only exist at the fringes of society.

It opens quietly enough in Baltimore in Reagan-era America, with teenage Maren (Taylor Russell) sneaking out of her bedroom window for a pyjama party with school friends. Her father had bolted her door, which was odd, and we find out why soon enough when she chomps down on something she wasn’t meant to.

She and Dad flee town, again. He finally leaves with a note saying he cannot protect her any more, which sends her to Minnesota on the trail of her mother who she knows little about. The thing about eaters, as they call themselves, is that they nose each other out and Maren first meets Sully (Mark Rylance), who smelt her coming a mile away. He is older and a touch sinister, and she hangs with him but not for long.

Then she meets the cannibal drifter Lee (Timothée Chalamet, from Dune and Call Me By Your Name), who is cool and intense with jeans so ripped they barely hang together. They begin the kind of teen romance in which misunderstood youth bond sweetly over shared interests. “Who was your first?” Lee asks. “The babysitter,” she replies. “Me too!” he says, and they laugh and feel seen.

The cannibalism is a lot to take, especially when stripped of its camp, True Blood-style context. These aren’t vampires who sprouts fangs and need human blood to survive. They are ordinary people who have an inexplicable, gruesome addiction to human flesh and they do it for the rush, not because they need to. There are some very confronting bloodied mouths and wet munching woven into the plot.

But this less a horror movie and more a horrifying story about otherwise normal people who even in their depravity seek a moral structure. There are rules among eaters and they make their choices, but Maren, in particular, has bouts of self-loathing. After one incident, she is so remorseful she convinces Lee to do the junkie’s version of going straight, and to just “be people, at least for a little while”.

It is all strangely moving, beautifully filmed – often at sunset under the open skies of America’s Midwest – and with a provocative tenderness that feels almost shameful to admit to.

The director, Luca Guadagnino (Call Me By Your Name), is drawn to wildness and has a gift for empathy that he has shown before, particularly in the underrated TV series We Are Who We Are, about a weird and rebellious teenage boy on a military base in Italy who he insists we get to know.

Bones and All won him the Silver Lion for best director at Venice and it is an exceptionally daring film that probably few will see. We never condone Maren and Lee, but we do feel for them as victims of inter-generational addiction who struggle with otherness.

All this makes Guadagnino a particularly interesting choice as director of the upcoming Burial Rites, starring Jennifer Lawrence and based on Adelaide writer Hannah Kent’s harrowing story of the last woman to be hanged in Iceland.

Bones and All is in cinemas now.