Maureen (Kristen Stewart) is a 28 year-old American living in Paris. During the day she works as a personal shopper for a rich celebrity named Kyra (Nora von Waldstätten). In her own time she obsesses over her recently deceased twin brother Lewis, and his promise to try and contact her from beyond the grave if he died. It is not long before something seems to be making contact, but whether it is her brother, her imagination or something altogether darker remains to be seen.

My hands-down favourite film from 2016 was Personal Shopper, a fantastic slow-burn thriller from the acclaimed French director Olivier Assayas. I have been a fan of his work since discovering his remarkable drama Irma Vep in 1996, in which Hong Kong actress Maggie Cheung played herself as the hapless star of a French movie remake of Les Vampires. Despite having seen a number of his other films since, it has taken until Personal Shopper for Irma Vep to be supplanted as my favourite. This is a tremendous film.

Personal Shopper is a horror story by stealth. At a glance it appears to be a typical French drama, with sullenly emotional and privileged characters complaining incessantly about their lives. Instead it develops into one of the best supernatural thrillers of recent years, and it has an alarming tendency to creep up on you and give one hell of a surprise. The film employs a wonderful slow burn, taking its time to establish Maureen, her job and her day-to-day life. She has a job that is simultaneously easy, well-paid and utterly demeaning. Each day she goes to expensive fashion stores and jewellers to select and pay for expensive couture outfits that her employer then wears at society parties, fashion festivals and red carpet events. The job might be bearable if her employer was a nice person, but she isn’t: Von Waldstätten gives a brief but wonderfully unlikable performance as the worst kind of high society diva.

The first trace of a supernatural element comes quite quickly, but like much of the film it is remarkably subtle. Maureen clearly wants to believe that there is something reaching out from beyond the grave, but there is always the chance that whatever she thinks is contacting her in entirely in her own head. When whatever is contacting her starts to converse via text messaging, another ambiguous possibility opens itself: that there may be a real person stalking her. The film keeps its secrets very close to its chest, gradually developing Personal Shopper into a supremely tense thriller. There are a lot of layers interweaved throughout the film, combining all kinds of thrillers together: some supernatural, some psychological, some erotic, and all mixed in and out until it’s difficult to tease out precisely what is happening. Some viewers are going to find the ambiguity infuriating: I thought it was one of the film’s greatest strengths.

Kristen Stewart is utterly remarkable as Maureen, presenting a depth and an intensity I had not previously seen her deliver. I had already heard extremely positive things about her Cesar-winning performance in Assayas’ previous film The Clouds of Sils Maria, and shortly after seeing Personal Shopper last year I tracked that film down and watched it for myself. Between both productions she does the best work I have seen her do. The sooner film-goers unshackle her remarkable talent from the commercial fare she undertook earlier in her career – Twilight, Snow White and the Huntsman and the like – the sooner they will come to appreciate what an outstanding performer she is. She is the critical component to Personal Shopper: so much of the film is anchored around Maureen’s subjective experience that a sub-par performance would ruin the entire film. Thankfully Stewart does not only meet the material but actively and extensively enhances it.

Olivier Assayas has crafted a challenging but deeply effective film. It uses a minimal musical score, really only present in transitions between scenes. Without the music the entire environment seems much more realistic – almost banal – and the film’s most frightening moments thus take on a much deeper intensity. The slow, measured photography is wonderful too, with careful movements and clever framing. Assayas clearly knows how to frame supernatural horror, and the fact that he shows such restraint in presenting that horror makes this exceptional film all the stronger. After a festival run last year Personal Shopper is finally getting a full theatrical release in Australia. I emphatically urge you to track it down. Films this good are rare.

A version of this review was previously published at The Angriest.