Olivier Assayas’ latest film tells two stories; one about a young professional woman working as an assistant for a famous celebrity, spending her days buying thousand-dollar belts and invaluable jewellery, recognising both the emptiness and seductive power of material possessions. The other is about a medium who is mourning the loss of her twin brother, trying to communicate with him in the afterlife, and being tormented by visions and spirits.

Of course, because this is an Olivier Assayas film, these two seemingly disparate stories are the experiences of the same woman, played by Kristen Stewart.

“It’s like when you’re at an arts exhibition and the card beside the painting says ‘mixed materials,’” laughs Assayas, referring to his intriguing blend of genres. “It’s mixed materials filmmaking.”

The Parisian has indeed put a unique spin on a traditional ghost story – in fact, he’s trying to redefine what we think of as ghosts. For him, believing in the supernatural is not a leap; we just have to look at ourselves to recognise that we’re constantly engaging with inexplicable energies.

“This story is really about someone trying to reconnect both with herself and her lost brother,” explains the 62-year-old director. “It’s about loneliness, about how you sustain yourself in a time of crisis and it’s also about your fears. Dealing with the paranormal and supernatural – it’s something we all have some experience of, in the sense that we all know that within our imagination and thought process is something that’s in our subconscious. We don’t have a clear hold on it, so we’re moved by forces we can’t see or understand. When we talk about the invisible and paranormal, we’re using very loaded words, but we’re using them to define some dark area within our psyche. And in movies, you can try be a bit literal about that dark part of ourselves.”

Assayas also enjoyed taking a modern approach to how we communicate with both ourselves and others. Kristen Stewart’s character Maureen describes herself as a medium, which may evoke images of crystal balls, tarot cards and seances, but Assayas’ vision is much more grounded in technology and science than one would expect. In Personal Shopper, invisible forces engage with modern technology, opening elevators and automatic doors, and sending eerie text messages to Maureen.

“I liked the idea of a movie set in a world where communication with the other side is possible,” says Assayas. “It’s not like other horror movies where you have to enter a different reality to encounter them. I wanted to have characters who could communicate with other beings and have that be part of their life experience. And I wanted to connect the film with the period where this felt natural, which was the late 19th century.
There were extraordinary things happening in science that would have been considered unreal or magical just a few years before. You could communicate across oceans, you could capture movements with photographs, you could see through the body with X-rays. So why not communicate with the dead? For a few decades at the end of the 19th century, spiritism was connected with science more than anything else. I liked the idea of transcribing that reality in modern Paris.”

This is the second time he’s worked with Stewart, who became the first American to win the Cesar Award For Best Supporting Actress for her performance in Assayas’ Clouds Of Sils Maria. The director reveals he felt compelled to work with the 26-year-old again.

“I wanted to go further with Kristen after we worked together on Clouds Of Sils Maria,” he says, “because I felt frustrated with my own writing. When I wrote Clouds Of Sils Maria, I was really writing for Juliette Binoche who plays the lead, and Kristen’s character Valentine was a bit more one-dimensional. She was just a young, no-nonsense American girl, but I think what Kristen made of that part was amazing. So my thought was, ‘What would she make of a more complex part and where would she take it?’ That was very stimulating for me when I was writing. And she’s wonderful to work with, she has a quest for authenticity that’s most exciting.”

Despite Stewart’s beautifully brittle performance and Assayas’ passion for the project, Personal Shopper has been divisive, with the film even being met by prolonged booing at its Cannes screening. The director doesn’t seem too worried.

“Cannes is a very exciting place for that!” he says, clearly taking the controversy in his stride. “Part of the fun in making something like Personal Shopper is that I know it’s not going to be conventional. What’s exciting in cinema is to try things that have not been done – while also making them entertaining. A lot of pure experimental cinema can be very boring. I want to take people into weird areas while also giving them some pleasure. And the people who boo it? They’re enjoying themselves too, in some way.”

That’s the spirit.

Personal Shopper is in cinemas from March 17.